Knee instruments and methods

ABSTRACT

Knee arthroplasty instrument systems directly reference and align with the anterior distal femoral cortex and the mechanical axis of the leg. The anterior femoral resection is aligned in the same plane as the anterior distal femoral cortex. The center of the femoral head, the medial/lateral center of the distal femur, the medial/lateral center of the proximal tibia, and the second toe, medial/lateral center of the ankle, or anterior tibial spine are all aligned to the mechanical axis of the leg. Methods of using a cut guide assembly and referencing a provisional proximal tibial resection at the base of the tibial eminence are disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of:

U.S. application Ser. No. 15/630,555, filed Jun. 22, 2017, entitled KNEEINSTRUMENTS AND METHODS.

U.S. application Ser. No. 15/630,555 claims the benefit of:

U.S. Provisional Application Ser. No. 62/353,553, filed Jun. 22, 2016,entitled KNEE INSTRUMENTS AND METHODS.

U.S. application Ser. No. 15/630,555 is a continuation-in-part of:

U.S. application Ser. No. 15/081,828, filed Mar. 25, 2016, entitled KNEEINSTRUMENTS AND METHODS.

U.S. application Ser. No. 15/081,828 claims the benefit of:

U.S. Provisional Application Ser. No. 62/138,307, filed Mar. 25, 2015,entitled KNEE INSTRUMENTS AND METHODS; and

U.S. Provisional Application Ser. No. 62/302,787, filed Mar. 2, 2016,entitled KNEE INSTRUMENTS AND METHODS.

The foregoing are incorporated by reference as though set forth hereinin their entirety.

TECHNICAL FIELD

The present disclosure relates to instruments and methods to improvefemoral and tibial alignment during knee arthroplasty. Morespecifically, the present disclosure relates to instruments and methodsto reference and align with the anterior distal femoral cortex, themechanical axis of the leg, and Whiteside's line (while intact, prior toany distal femoral resection). While this disclosure is made in thecontext of knee arthroplasty, the principles are applicable to alignmentduring other arthroplasty procedures.

BACKGROUND

Traditional total knee arthroplasty instruments utilize intramedullaryinstruments to determine proper distal femur saw cut alignment, andextramedullary instruments to align the saw cut for the proximal tibia.Therefore it is acceptable to prepare the distal femur separate from theproximal tibia. There exists no conjoined effort to cut the distal femurand the proximal tibia as the single lower extremity body part whichconstitutes the knee joint.

This contemporary instrumentation process violates the principlesestablished by Insall in the 1970s. Popular total knee arthroplastyinstruments teaches this inexact intramedullary instrument processbecause it is simpler to teach, understand and utilize by most surgeons.

Dr. Insall recognized the need for external rotation (ER) of the femoralcomponent when performing a total knee arthroplasty (TKA). In 1990 Dr.Insall attributed the need for approximately 3 degrees of ER to an“abundance of soft tissue in the posteromedial corner of the knee.”

Indeed in the absence of this prescribed ER of the femoral component 1)patellar tracking will be unbalanced, related to the trochlear grooveand 2) the medial compartment will be compressed significantly greaterthan the lateral compartment with the knee flexed beyond 40 degrees and3) the patella would track laterally.

The reason for alteration of the normal morphology of the distal femurwhen performing a TKA is not well understood.

The reason for the need to externally rotate the femoral condyleapproximately 3 degrees relative to the normal morphology of the femoralcondyles is the clue to surgical alteration of normal morphology of theproximal tibia.

Normal Anatomy of the Proximal Tibia

As is well known, in a lateral xray of a normal proximal tibia, theplane of the medial tibial plateau exists approximately 3 mm more distalthan the lateral tibial plateau.

Evident in a CAT scan of a normal knee is the elevation differencebetween the planes of the two tibial plateaus.

If a saw cut is made at the proximal tibia, at a right angle to thevertical axis of the tibia, the medial tibial compartment will beelevated relative to the lateral tibial plateau. This relative elevationwill, in turn, elevate the medial femoral condyle, necessitating removalof an equal amount of posterior medial femoral condyle (equal to therelative elevation of the medial tibial plateau) in order to maintainproper tracking of the patellar throughout flexion and extension of theknee. It is the external rotation of approximately 3 degrees (3 mm) thataccomplishes about 3 mm more removal of the condyle on the medial sidethan the lateral side.

The most common adjustment position for “external rotation guides” is 3degrees. This position will remove about 3 mm more off the medialfemoral condyle than the lateral femoral condyle. The reality is, andtherefore the error is, that condylar and plateau articular cartilagewear, and differences in plateau height between the medial and lateralplateaus, will require external rotation adjustments between 1 degreeand 6 degrees in order to balance compression forces in the medial andlateral compartments for both flexion and extension.

It is only after equal compartment compression is accomplished throughproper external rotation that proper ligament releases can beaccomplished.

Method for Getting External Rotation Right

Equal compression of the medial and lateral compartments can only beobtained by causing the posterior femoral condylar cut to be parallel tothe proximal tibial cut.

To accomplish this:

Pin the tibial cut guide in place with the tibial alignment rodcentering distally over the middle of the plafond. The plafond is theceiling of the ankle joint, that is, the articular surface of the distalend of the tibia.

After resecting the distal femur, place the 4-in-1 femoral cut guide inplace over the cut surface of the distal femur. Hang the 4-in-1 cuttingguide on a centrally placed pin on Whiteside's line located just belowthe cut slot for the anterior femoral resection. This cut slot locationreferences the distal/anterior femoral cortex for proper anteriorresection. The centrally placed pin may optionally be replaced by aprotruding post located on the bone-contacting side of the 4-in-1 cutguide that fits into a corresponding hole in the femur.

Utilizing the proper sized 4-in-1 cut guide, this guide is now “rotated”until the posterior cut slot is parallel with the cut slot on the tibialcut guide.

Appropriate fixation pins/screws secure the femoral and tibial cutguides. All cuts can now be made, assuring proper patellar tracking.

Equal and rectangular gaps can be expected in both flexion andextension. Soft tissue releases are now performed to further balancecompression forces in the medial and lateral compartments.

At least the following aspects of this disclosure are believed to benovel and non-obvious contributions over the prior art of kneearthroplasty:

Reference of distal anterior femur (DAF) and exact location of femoralhead to accomplish exact knowledge of 1) varus/valgus of distal femoralcut, and 2) flexion/extension of anterior and posterior femoral cuts.Both data points are contained in the position of a distal femoral pinor hole.

Determination of proper External Rotation of femur by “hanging” theupper-center portion of a 4-in-1 femoral cutting block on the distalfemoral pin, which is in the center of the trochlear groove. Theproximal/distal axis through the center of the block is aligned with thelongitudinal axis of the tibia, which aligns the trochlear groove of thefemur (Whiteside's line) with the axis of the tibia at 90 degreesflexion of the knee. The distal femoral pin may optionally be replacedby a protruding post located on the bone-contacting side of the 4-in-1cut guide that fits into a corresponding hole in the femur.

With proper ER of the femoral component, the posterior femoral cut andthe proximal tibial cut will be parallel at 90 degrees knee flexion.Therefore the 4-in-1 femoral cutting block can be extended to a 5-in-1cutting block by adding the proximal tibial cut slot.

The 5-in-1 (effective) block is attached superiorly (proximally) at thedistal femoral pin or hole and distally to the tibial alignment rodextending to the middle of the ankle. The patellar will now trackproperly.

With the rectangular gap at the femur and tibia, equal compression willexist between medial and lateral compartments of the knee both inflexion and extension.

Other:

Finding the femoral head.

Bar fixed to operating table over the area of the femoral head with goalpost marker/target.

Ultrasound method of locating femoral head.

Guide to reference DAF and then connect to femoral head goal post/targetto determine distal femoral pin location. Arthroscopic procedurecontemplated.

Adjustable 4-in-1 femoral cut guide.

This disclosure teaches bony and soft tissue preparation of the kneejoint utilizing instruments and techniques consistent with proven totalknee arthroplasty instruments principles.

SUMMARY

The various systems and methods of the present technology have beendeveloped in response to the present state of the art, and inparticular, in response to the problems and needs in the art that havenot yet been fully solved by currently available knee arthroplastyinstrument systems and methods. The systems and methods of the presenttechnology may provide more objective, repeatable alignment relative toimportant biomechanical features, compared to current systems andmethods.

More specifically, the present disclosure relates to instruments andmethods to reference and align with the anterior distal femoral cortex,the mechanical axis of the leg, and Whiteside's line (while intact,prior to any distal femoral resection). The anterior femoral resectionis aligned in the same plane as the anterior distal femoral cortex. Thecenter of the femoral head, the medial/lateral center of the distalfemur, the medial/lateral center of the proximal tibia, and the secondtoe, medial/lateral center of the ankle, or anterior tibial spine orcrest are all simultaneously aligned to the mechanical axis of the legwhile the leg is in full extension and the knee joint is distracted. Thedistal femoral and proximal tibial resections are aligned relative tothe mechanical axis of the leg. Since the distal femoral and proximaltibial resections may be made with the leg in full extension, a muchsmaller incision may be required, particularly in the quadriceps region.An eight to ten inch long incision, typical of the current state of theart, may be shortened to about six inches, with most of the savingsoccurring proximally in the quadriceps region. Whiteside's line isreferenced while the distal femur is intact, before any distal femoralresection, and the anterior and posterior femoral resections and chamfercuts are aligned to this reference using a jig.

The systems and methods disclosed herein provide a simple and fast wayto objectively and precisely align the knee joint during arthroplastyprocedures. This is inherently advantageous because malalignmentpredisposes a reconstructed knee to premature failure. This isparticularly advantageous for those surgeons who must perform kneearthroplasty from time to time, but whose knee arthroplasty procedurevolume is low. Eighty percent of knee arthroplasty procedures areperformed by surgeons who do no more than two knee arthroplastyprocedures per month.

The systems disclosed herein provide a cost-effective mechanicalalternative to surgical navigation systems, particularly because thedisclosed systems include components that are readily made as disposableitems. The femoral and tibial alignment components, for example, arecontemplated to be disposable items.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the technology will become more fully apparentfrom the following description and appended claims, taken in conjunctionwith the accompanying drawings. Understanding that these drawings depictonly exemplary embodiments and are, therefore, not to be consideredlimiting of the scope of the technology, the exemplary embodiments willbe described with additional specificity and detail through use of theaccompanying drawings in which:

FIG. 1 is a perspective view of an instrument base;

FIG. 2 is a side view of the base of FIG. 1 assembled with a handle anda drill guide;

FIG. 3 is a front view of the assembly of FIG. 2;

FIG. 4 is a side view of the base of FIG. 1 assembled with a cut guideassembly;

FIG. 5 is a top view of the assembly of FIG. 4;

FIG. 6 is a front view of the assembly of FIG. 4;

FIG. 7 is a side view of certain anatomical structures of the human kneein cross section;

FIG. 8 is a top view of a step in a surgical procedure, elevating thesuprapatellar fat pad;

FIG. 9 is a top view of a step in a surgical procedure, inserting thebase of FIG. 1 against the anterior distal femoral cortex;

FIG. 10 is a top view of a step in a surgical procedure, aligning afemoral extension rod over the center of the femoral head and themedial/lateral center of the distal femur to establish a mechanical axisof the leg;

FIG. 11 is a top view of a step in a surgical procedure, aligning afemoral cut guide to the mechanical axis of the leg;

FIG. 12 is a front view of the cut guide assembly of FIG. 4 configuredfor making femoral cuts;

FIG. 13 is a side view of the surgical step of FIG. 11;

FIG. 14 is a top view of a step in a surgical procedure, aligning atibial cut guide to the anterior tibia;

FIG. 15 is a front view of the cut guide assembly of FIG. 4 configuredfor making a tibial cut;

FIG. 16 is a side view of the surgical step of FIG. 14 illustrating theuse of a joint distraction member;

FIG. 17 is a side view of the surgical step of FIG. 14 illustrating theuse of another joint distraction member;

FIG. 18 is a front view of certain anatomical landmarks and geometry ofthe human knee and leg;

FIG. 19 is a side view of certain anatomical landmarks and geometry ofthe human knee;

FIG. 20 is a perspective view of the femur and tibia of the human knee;

FIG. 21A is a perspective view of another instrument system; and FIG.21B is an enlarged detail view of a portion of the instrument system ofFIG. 21A;

FIG. 22A is a top view of the instrument system of FIG. 21A; and FIG.22B is an enlarged detail view of a portion of the instrument system ofFIG. 22A;

FIG. 23A is a side view of the instrument system of FIG. 21A; and FIG.23B is an enlarged detail view of a portion of the instrument system ofFIG. 23A;

FIG. 24A is a perspective view of a base of the instrument system ofFIG. 21A; and FIG. 24B is another perspective view of the base of FIG.24A from a different direction;

FIG. 25A is a perspective view of a femoral riser, or handle, of theinstrument system of FIG. 21A; and FIG. 25B is another perspective viewof the femoral riser of FIG. 25A from a different direction;

FIG. 26A is a perspective view of a femoral extension rod of theinstrument system of FIG. 21A; and FIG. 26B is another perspective viewof the femoral extension rod of FIG. 26A from a different direction;

FIG. 27A is a perspective view of a tapered plug assembly of theinstrument system of FIG. 21A; FIG. 27B is an exploded perspective viewof the tapered plug assembly of FIG. 27A; and FIG. 27C is anotherexploded perspective view of the tapered plug assembly of FIG. 27A froma different direction;

FIG. 28A is a perspective view of a tibial-femoral pin guide of theinstrument system of FIG. 21A; and FIG. 28B is another perspective viewof the tibial-femoral pin guide of FIG. 28A from a different direction;

FIG. 29A is a perspective view of a tibial riser of the instrumentsystem of FIG. 21A; and FIG. 29B is another perspective view of thetibial riser of FIG. 29A from a different direction;

FIG. 30A is a perspective view of a tibial outer extension rod of theinstrument system of FIG. 21A; and FIG. 30B is another perspective viewof the tibial outer extension rod of FIG. 30A from a differentdirection;

FIG. 31A is a perspective view of a first tibial inner extension rod ofthe instrument system of FIG. 21A; and FIG. 31B is another perspectiveview of the first tibial inner extension rod of FIG. 31A from adifferent direction;

FIG. 32A is a perspective view of a second tibial inner extension rod ofthe instrument system of FIG. 21A; and FIG. 32B is another perspectiveview of the second tibial inner extension rod of FIG. 32A from adifferent direction;

FIG. 33A is a perspective view of a femoral cut guide of the instrumentsystem of FIG. 21A; and FIG. 33B is another perspective view of thefemoral cut guide of FIG. 33A from a different direction;

FIG. 34A is a perspective view of a tibial cut guide of the instrumentsystem of FIG. 21A; and FIG. 34B is another perspective view of thetibial cut guide of FIG. 34A from a different direction;

FIG. 35 is a perspective view of a femoral base block assembly;

FIG. 36A is a perspective view of a femoral base block of the femoralbase block assembly of FIG. 35; and FIG. 36B is another perspective viewof the femoral base block of FIG. 36A from a different direction;

FIG. 37 is a perspective view of a translation bar of the femoral baseblock assembly of FIG. 35;

FIG. 38A is a perspective view of a knob of the femoral base blockassembly of FIG. 35; and FIG. 38B is another perspective view of theknob of FIG. 38A from a different direction;

FIG. 39A is a perspective view of a top component of the femoral baseblock assembly of FIG. 35; and FIG. 39B is another perspective view ofthe top component of FIG. 39A from a different direction;

FIG. 40A is a perspective view of a bottom component of the femoral baseblock assembly of FIG. 35; and FIG. 40B is another perspective view ofthe bottom component of FIG. 40A from a different direction;

FIG. 41A is a perspective view of a socket of the femoral base blockassembly of FIG. 35; and FIG. 41B is another perspective view of thesocket of FIG. 41A from a different direction;

FIG. 42A is a perspective view of another translation bar, a slide, acut guide, and a condyle probe, all for substitution into the femoralbase block assembly of FIG. 35; and FIG. 42B is another perspective viewof the translation bar, slide, cut guide, and condyle probe of FIG. 42Afrom a different direction;

FIG. 43A is a perspective view of the translation bar of FIG. 42A; andFIG. 43B is another perspective view of the translation bar of FIG. 43Afrom a different direction;

FIG. 44A is a perspective view of the slide of FIG. 42A; and FIG. 44B isanother perspective view of the slide of FIG. 44A from a differentdirection;

FIG. 45A is a perspective view of the cut guide of FIG. 42A; and FIG.45B is another perspective view of the cut guide of FIG. 45A from adifferent direction;

FIG. 46 is a perspective view of the condyle probe of FIG. 42A;

FIG. 47A is a perspective view of yet another instrument system, showingan assembly of components similar to those shown in FIG. 21A; and FIG.47B is an enlarged detail view of a portion of the instrument system ofFIG. 47A;

FIG. 48A is a top view of the instrument system of FIG. 47A; and FIG.48B is an enlarged detail view of a portion of the instrument system ofFIG. 48A;

FIG. 49A is a side view of the instrument system of FIG. 47A; and FIG.49B is an enlarged detail view of a portion of the instrument system ofFIG. 49A;

FIG. 50A is a perspective view of a base and a femoral riser assembly ofthe instrument system of FIG. 47A; and FIG. 50B is another perspectiveview of the base and femoral riser assembly of FIG. 50A from a differentdirection;

FIG. 51A is a perspective view of the base of FIG. 50A; FIG. 51B isanother perspective view of the base of FIG. 51A from a differentdirection; FIG. 51C is a perspective view of a cam for use with the baseof FIG. 50A; and FIG. 51D is another perspective view of the cam from adifferent direction;

FIG. 52A is a perspective view of a femoral pin guide of the femoralriser assembly of FIG. 50A; and FIG. 52B is another perspective view ofthe femoral pin guide of FIG. 52A from a different direction;

FIG. 53A is a perspective view of a handle of the femoral riser assemblyof FIG. 50A; and FIG. 53B is another perspective view of the handle ofFIG. 53A from a different direction;

FIG. 54A is an exploded perspective view of a femoral extension rodassembly of the instrument system of FIG. 47A; and FIG. 54B is anotherexploded perspective view of the femoral extension rod assembly of FIG.54A from a different direction;

FIG. 55A is a perspective view of a distal femoral condyle block for usewith the instrument system of FIG. 47A; and FIG. 55B is anotherperspective view of the distal femoral condyle block of FIG. 55A from adifferent direction;

FIG. 56A is a perspective view of an angle block assembly for use withthe instrument system of FIG. 47A; and FIG. 56B is another perspectiveview of the angle block assembly of FIG. 56A from a different direction;

FIG. 57A is an exploded perspective view of the angle block assembly ofFIG. 456A; and FIG. 57B is another exploded perspective view of theangle block assembly of FIG. 57A from a different direction;

FIG. 58A is an exploded perspective view of a Whiteside's angle gageassembly for use with the angle block assembly of FIG. 56A; and FIG. 58Bis another exploded perspective view of the Whiteside's angle gageassembly of FIG. 58A from a different direction;

FIG. 59A is a perspective view of a cut guide mounting block assemblyfor use with the angle block assembly of FIG. 56A; and FIG. 59B isanother perspective view of the cut guide mounting block assembly ofFIG. 59A from a different direction;

FIG. 60 is an exploded perspective view of the cut guide mounting blockassembly of FIG. 59A;

FIG. 61A is a perspective view of a four-in-one cut guide for use withthe cut guide mounting block assembly of FIG. 59A; and FIG. 61B isanother perspective view of the four-in-one cut guide of FIG. 61A from adifferent direction;

FIG. 62A is an exploded perspective view of a tibial connection block, atibial pin guide, and a tibial riser of the instrument system of FIG.47A; and FIG. 62B is another exploded perspective view of the tibialconnection block, pin guide, and riser of FIG. 62A from a differentdirection;

FIG. 63A is a perspective view of a femoral support arm assembly for usewith the instrument system of FIG. 47A; and FIG. 63B is anotherperspective view of the femoral support arm assembly of FIG. 63A from adifferent direction;

FIG. 64A is an exploded perspective view of the femoral support armassembly of FIG. 63A; and FIG. 64B is another exploded perspective viewof the femoral support arm assembly of FIG. 64A from a differentdirection;

FIG. 65A is a perspective view of a target clamp assembly for use withthe femoral support arm assembly of FIG. 63A; FIG. 65B is anotherperspective view of the target clamp assembly of FIG. 65A from adifferent direction; and FIG. 65C is yet another perspective view of thetarget clamp assembly of FIG. 65A from another different direction;

FIG. 66A is an exploded perspective view of the target clamp assembly ofFIG. 65A; and FIG. 66B is another exploded perspective view of thetarget clamp assembly of FIG. 66A from a different direction;

FIG. 67A is a perspective view of a foot holder assembly for use withthe instrument system of FIG. 47A; and FIG. 67B is another perspectiveview of the foot holder assembly of FIG. 67A from a different direction;

FIG. 68A is an exploded perspective view of the foot holder assembly ofFIG. 67A, the foot holder omitted for clarity; and FIG. 68B is anotherexploded perspective view of the foot holder assembly of FIG. 68A from adifferent direction;

FIG. 69 is a perspective view of a femur, tibia, and fibula, showing thefemoral support arm assembly of FIG. 63A;

FIG. 70 is a perspective view of the femur, tibia, fibula, and femoralsupport arm assembly of FIG. 69 after performing a provisional proximaltibial resection;

FIG. 71 is a perspective view of the femur, tibia, fibula, and femoralsupport arm assembly of FIG. 70, after coupling the target clampassembly of FIG. 65A to the femoral support arm assembly;

FIG. 72A is a perspective view of the femur, tibia, fibula, femoralsupport arm assembly, and target clamp assembly of FIG. 71, afterpositioning the base of FIG. 47A on the anterior distal femur, extendingthe femoral extension rod assembly of FIG. 47A through the target of thetarget clamp assembly, and coupling the distal femoral condyle block ofFIG. 55A to the femoral riser assembly; and FIG. 72B is a top view ofthe femur, tibia, fibula, femoral support arm assembly, target clampassembly, base, femoral riser assembly, distal femoral condyle block,and femoral extension rod assembly of FIG. 72A;

FIG. 73 is a perspective view of the femur, tibia, fibula, base, femoralriser assembly, and distal femoral condyle block of FIG. 72A, afterfixing the femoral riser assembly to the anterior distal femur withpins;

FIG. 74 is a perspective view of the femur, tibia, fibula, base, andfemoral riser assembly of FIG. 73, after removing the distal femoralcondyle block;

FIG. 75 is a perspective view of the femur, tibia, fibula, base, andfemoral riser assembly of FIG. 74, after attaching the angle blockassembly of FIG. 56A;

FIG. 76 is a perspective view of the femur, tibia, fibula, base, femoralriser assembly, and angle block assembly of FIG. 75, after coupling theWhiteside's line gage assembly of FIG. 58A to the angle block assembly;

FIG. 77 is a distal view of the femur, tibia, base, femoral riserassembly, angle block assembly, and Whiteside's line gage assembly ofFIG. 76, after locking the Whiteside's line gage assembly in anorientation parallel to Whiteside's line;

FIG. 78 is a perspective view of the femur, tibia, fibula, base, andfemoral riser assembly of FIG. 77, after removing the Whiteside's linegage assembly and the angle block assembly, reattaching the distalfemoral condyle block of FIG. 55A to the femoral riser assembly, andmaking a distal femoral resection guided by the distal femoral condyleblock;

FIG. 79 is a perspective view of the femur, tibia, fibula, base, andfemoral riser assembly of FIG. 78 after again removing the distalfemoral condyle block;

FIG. 80A is a perspective view of the femur, tibia, fibula, base, andfemoral riser assembly of FIG. 79, after coupling the tibial connectionblock of FIG. 47A to the femoral riser assembly, coupling the tibial pinguide to the tibial connection block, placing the knee joint in fullextension, and securing the foot in the foot holder assembly of FIG.67A; FIG. 80B is a top view of the femur, tibia, fibula, base, femoralriser assembly, tibial connection block, tibial pin guide, and footholder assembly of FIG. 80A; and FIG. 80C is a top view of the femur,tibia, fibula, base, femoral riser assembly, tibial connection block,tibial pin guide, and foot holder assembly of FIG. 80B after aligningthe tibia to the mechanical axis of the leg;

FIG. 81 is a perspective view of the femur, tibia, fibula, base, andfemoral riser assembly of FIG. 80A, after removing the tibial connectionblock and tibial pin guide and reattaching the angle block assembly ofFIG. 77 to the femoral riser assembly;

FIG. 82 is a perspective view of the femur, tibia, fibula, base, femoralriser assembly, and angle block assembly of FIG. 81, after coupling thecut guide mounting block assembly of FIG. 59A to the angle blockassembly;

FIG. 83 is a perspective view of the femur, tibia, fibula, base, femoralriser assembly, angle block assembly, and cut guide mounting blockassembly of FIG. 82, after coupling the four-in-one cut guide of FIG.61A to the cut guide mounting block assembly;

FIG. 84 is a perspective view of the femur, tibia, fibula, base, femoralriser assembly, angle block assembly, cut guide mounting block assembly,and four-in-one cut guide of FIG. 83 after aligning the four-in-one cutguide against the distal femoral resection;

FIG. 85 is a perspective view of the femur, tibia, fibula, andfour-in-one cut guide of FIG. 85, after fixing the four-in-one cut guideto the distal femoral resection, removing the base, femoral riserassembly, cut guide mounting block assembly, and angle block assembly,and making an anterior femoral resection guided by the four-in-one cutguide;

FIG. 86A is a bottom view of a femoral head finder; and FIG. 86B is aside view of the femoral head finder of FIG. 86A;

FIG. 87A is a front view of a collar; and FIG. 87B is a side view of thecollar of FIG. 87A;

FIG. 88 is an isometric view of a knee joint with implanted femoralcomponent, tibial component, articular insert, and patellar component,the patellar component shown exploded from the patella for clarity;

FIG. 89 is a perspective view of a femur, tibia, and fibula with a footreceiver and a lower bar of a foot holder assembly;

FIG. 90 is a perspective view of the femur, tibia, fibula, footreceiver, and lower bar of FIG. 89 with a femoral support arm assembly;

FIG. 91 is a perspective view of the femur, tibia, fibula, footreceiver, lower bar, and femoral support arm assembly of FIG. 90 with afemoral head finder coupled to the femoral support arm assembly;

FIG. 92 is a perspective view of the femur, tibia, fibula, footreceiver, lower bar, femoral support arm assembly, and femoral headfinder of FIG. 91 with a collar coupled to the femoral support armassembly next to the femoral head finder;

FIG. 93 is a perspective view of the femur, tibia, fibula, footreceiver, lower bar, femoral support arm assembly, and collar of FIG. 92with a target clamp assembly coupled to the femoral support arm assemblynext to the collar;

FIG. 94 is a perspective view of the femur, tibia, fibula, footreceiver, lower bar, femoral support arm assembly, collar, and targetclamp assembly of FIG. 93 with a complete foot holder assembly includinga bridge, target mounting block, dovetail lock, target, and thumbscrewcoupled to the lower bar and the foot receiver;

FIG. 95A is a perspective view of the foot holder assembly of FIG. 94;FIG. 95B is an exploded perspective view of the foot holder assembly ofFIG. 94; and FIG. 95C is another exploded perspective view of the footholder assembly of FIG. 94 from a different direction;

FIG. 96A is a perspective view of the femur, tibia, fibula, femoralsupport arm assembly, collar, target clamp assembly, and foot holderassembly of FIG. 94 with a femoral pin guide assembly coupled to theanterior distal femur; and FIG. 96B is a detail perspective view of thefemur, tibia, fibula, and femoral pin guide assembly of FIG. 96A; and

FIG. 97A is a perspective view of the femoral pin guide assembly of FIG.96A; FIG. 97B is an exploded perspective view of the femoral pin guideassembly of FIG. 96A; and FIG. 97C is another exploded perspective viewof the femoral pin guide assembly of FIG. 96A from a differentdirection;

FIG. 98 is a perspective view of the femur, tibia, fibula, and femoralpin guide assembly of FIG. 96B with a femoral pin inserted through thefemoral pin guide assembly into the distal femur;

FIG. 99 is a perspective view of the femur, tibia, fibula, femoral pinguide assembly, and femoral pin of FIG. 98 with a pin sleeve of thefemoral pin guide assembly removed;

FIG. 100 is a perspective view of the femur, tibia, fibula, and femoralpin of FIG. 99 with the rest of the femoral pin guide assembly removed;

FIG. 101 is a perspective view of the femur, tibia, fibula, and femoralpin of FIG. 100 with a tibial pin inserted into the tibial tuberosity;

FIG. 102A is a perspective view of the femur, tibia, fibula, femoralpin, and tibial pin of FIG. 101 and the foot holder assembly of FIG. 96Awith a three in one cut guide assembly coupled to the femoral pin anddistal femur, the tibial pin and tibia, and the foot holder assembly viaa tibial extension rod assembly; and FIG. 102B is a lateral view of thefemur, tibia, fibula, femoral pin, tibial pin, foot holder assembly,three in one cut guide assembly, and tibial extension rod assembly ofFIG. 102A;

FIG. 103A is a perspective view of the three in one cut guide assemblyand tibial extension rod assembly of FIG. 102A; FIG. 103B is an explodedperspective view of the three in one cut guide assembly of FIG. 103A;and FIG. 103C is another exploded perspective view of the three in onecut guide assembly of FIG. 103A from a different direction;

FIG. 104 is a perspective view of the femur, tibia, fibula, femoral pin,tibial pin, three in one cut guide assembly, and tibial extension rodassembly of FIG. 102A with bone pins inserted through the three in onecut guide assembly into the distal femur and proximal tibia;

FIG. 105 is a perspective view of the femur, tibia, fibula, femoral pin,tibial pin, three in one cut guide assembly, tibial extension rodassembly, and pins of FIG. 104 after making an anterior femoralresection, a posterior femoral resection, and a proximal tibialresection through the three in one cut guide assembly;

FIG. 106 is a perspective view of the femur, tibia, fibula, femoral pin,tibial pin, anterior femoral resection, posterior femoral resection, andproximal tibial resection of FIG. 105 with the three in one cut guideassembly and related bone pins removed;

FIG. 107 is a perspective view of the femur, tibia, fibula, femoral pin,and tibial pin of FIG. 106 and a portion of the femoral support armassembly, collar, target clamp assembly, and a portion of the footholder assembly of FIG. 96A with a distal femoral cut guide assemblycoupled to the distal femur and the target clamp assembly via a femoralextension rod assembly;

FIG. 108A is a perspective view of the distal femoral cut guide assemblyof FIG. 107; FIG. 108B is an exploded perspective view of the distalfemoral cut guide assembly of FIG. 107; and FIG. 108C is anotherexploded perspective view of the distal femoral cut guide assembly ofFIG. 107 from a different direction;

FIG. 109 is a perspective view of the femur, tibia, fibula, femoral pin,tibial pin, distal femoral cut guide assembly, and a portion of thefemoral extension rod assembly of FIG. 107 with bone pins insertedthrough the distal femoral cut guide assembly into the distal femur;

FIG. 110 is a perspective view of the femur, tibia, fibula, tibial pin,distal femoral cut guide assembly, a portion of the femoral extensionrod assembly, and related bone pins of FIG. 109 after removing thefemoral pin and making a distal femoral resection;

FIG. 111A is a perspective view of the femur, tibia, fibula, tibial pin,distal femoral cut guide assembly, a portion of the femoral extensionrod assembly, and related bone pins of FIG. 110 with a distal femoralcut block assembly of the distal femoral cut guide assembly removed; andFIG. 111B is a lateral view of the femur, distal femoral cut guideassembly, a portion of the femoral extension rod assembly, and relatedbone pins of FIG. 111A;

FIG. 112 is a perspective view of the femur, tibia, fibula, tibial pin,distal femoral cut guide assembly, a portion of the femoral extensionrod assembly, and related bone pins of FIG. 111A with a chamfer cutguide coupled to a femoral pin block of the distal femoral cut guideassembly;

FIG. 113 is a perspective view of the chamfer cut guide of FIG. 112;

FIG. 114 is a perspective view of the femur, tibia, fibula, tibial pin,distal femoral cut guide assembly, a portion of the femoral extensionrod assembly, related bone pins, and chamfer cut guide of FIG. 112 withbone pins inserted through the chamfer cut guide into the distal femur;

FIG. 115A is a perspective view of the femur, tibia, fibula, tibial pin,distal femoral cut guide assembly, a portion of the femoral extensionrod assembly, related bone pins, chamfer cut guide, and related bonepins of FIG. 114 after making an anterior chamfer cut and a posteriorchamfer cut; and FIG. 115B is a lateral view of the femur, tibia,fibula, distal femoral cut guide assembly, a portion of the femoralextension rod assembly, related bone pins, chamfer cut guide, andrelated bone pins of FIG. 115A with an implant trial coupled to thechamfer cut guide;

FIG. 116A is a perspective view of the femur, tibia, fibula, femoralpin, tibial pin, three in one cut guide assembly, tibial extension rodassembly, and pins of FIG. 105 with a distal femoral cut guide coupledto the distal anterior femur and the three in one cut guide with bonepins; FIG. 116B is a perspective view of the distal femoral cut guide ofFIG. 116A; and FIG. 116C is a side view of the distal femoral cut guideof FIG. 116A;

FIG. 117A is a perspective view of the femur, tibia, fibula, distalfemoral cut guide, and pins of FIG. 116A after removing the femoral pinthree in one cut guide assembly and tibial extension rod assembly andmaking a distal femoral resection; and FIG. 117B is a lateral view ofthe femur, tibia, fibula, distal femoral cut guide, and pins of FIG.117A;

FIG. 118A is a perspective view of the femur, tibia, fibula, distalfemoral cut guide, and pins of FIG. 117A with a chamfer cut guidecoupled to the distal femur and the distal femoral cut guide with bonepins; and FIG. 118B is a lateral view of the femur, tibia, fibula,distal femoral cut guide, pins, and chamfer cut guide of FIG. 118A;

FIG. 119A is a perspective view of the femur, tibia, fibula, chamfer cutguide, and pins of FIG. 118A after making anterior and posterior chamfercuts; and FIG. 119B is a lateral view of the femur, tibia, fibula,chamfer cut guide, and pins of FIG. 119A;

FIG. 120 is a perspective view of the femur, tibia, and fibula with theanterior, distal, and posterior femoral resections, the anterior andposterior femoral chamfer cuts, and the proximal tibial resection withall instruments removed;

FIG. 121 is a perspective view of a femur, tibia, and fibula with a footreceiver and a lower bar of a foot holder assembly;

FIG. 122 is a perspective view of the femur, tibia, fibula, footreceiver, and lower bar of FIG. 121 with a femoral support arm assembly;

FIG. 123A is a perspective view of the femur, tibia, fibula, footreceiver, lower bar, and femoral support arm assembly of FIG. 122 with afemoral head finder coupled to the femoral support arm assembly; andFIG. 123B is a top view of the femur, tibia, fibula, foot receiver,lower bar, femoral support arm assembly, and femoral head finder of FIG.123A;

FIG. 124 is a perspective view of the femur, tibia, fibula, footreceiver, lower bar, femoral support arm assembly, and femoral headfinder of FIG. 123A with a collar coupled to the femoral support armassembly next to the femoral head finder;

FIG. 125 is a perspective view of the femur, tibia, fibula, footreceiver, lower bar, femoral support arm assembly, femoral head finder,and collar of FIG. 124 with a target clamp assembly coupled to thefemoral support arm assembly next to the collar;

FIG. 126 is a perspective view of the femur, tibia, fibula, footreceiver, lower bar, femoral support arm assembly, collar, and targetclamp assembly of FIG. 125 with a complete foot holder assemblyincluding a bridge, target mounting block, dovetail lock, target, andthumbscrew coupled to the lower bar and the foot receiver;

FIG. 127 is a perspective view of the femur, tibia, fibula, foot holderassembly, femoral support arm assembly, collar, and target clampassembly of FIG. 126 after making a provisional tibial resection;

FIG. 128A is a perspective view of the femur, tibia, fibula, foot holderassembly, femoral support arm assembly, collar, and target clampassembly of FIG. 127 with a femoral pin guide assembly coupled to theanterior distal femur and the target clamp assembly via a femoralextension rod assembly; and FIG. 128B is a top view of the femur, tibia,fibula, foot holder assembly, femoral support arm assembly, collar,target clamp assembly, femoral pin guide assembly, and femoral extensionrod assembly of FIG. 128A;

FIG. 129A is a perspective view of the femoral pin guide assembly ofFIG. 128A; and FIG. 129B is another perspective view of the femoral pinguide assembly of FIG. 128A from a different direction;

FIG. 130 is a perspective view of the femur, tibia, fibula, femoral pinguide assembly, and a portion of the femoral extension rod assembly ofFIG. 128A with femoral pins inserted through the femoral pin guideassembly into the distal femur;

FIG. 131 is a perspective view of the femur, tibia, fibula, femoral pinguide assembly, and a portion of the femoral extension rod assembly ofFIG. 128A with a pin sleeve of the femoral pin guide assembly and one ofthe femoral pins removed;

FIG. 132 is a perspective view of the femur, tibia, fibula, andremaining femoral pin of FIG. 131 with the rest of the femoral pin guideassembly removed;

FIG. 133A is a perspective view of the femur, tibia, fibula, and femoralpin of FIG. 132 and the foot holder assembly of FIG. 126 with a kneeangle guide coupled to the femoral pin; and FIG. 133B is a lateral viewof the femur, tibia, fibula, femoral pin, foot holder assembly, and kneeangle guide of FIG. 133A;

FIG. 134 is a perspective view of the femur, tibia, fibula, and femoralpin of FIG. 133A with the knee angle guide removed, with a distalfemoral cut guide assembly coupled to the femur and the femoral pin;

FIG. 135A is an exploded perspective view of the femoral pin and distalfemoral cut guide assembly of FIG. 134; and FIG. 135B is anotherexploded perspective view of the femoral pin and distal femoral cutguide assembly of FIG. 134 from a different direction;

FIG. 136 is a perspective view of the femur, tibia, fibula, and aportion of the distal femoral cut guide assembly of FIG. 134 aftermaking a distal femoral resection and removing the femoral pin and aninterlock and a distal plate of the distal femoral cut guide assembly;

FIG. 137A is a perspective view of the femur, tibia, and fibula of FIG.136 and the foot holder assembly of FIG. 133A with a femoral four-in-onecut guide assembly coupled to the distal femur and a proximal tibial cutguide coupled to the proximal tibia and the foot holder assembly via atibial extension rod assembly; FIG. 137B is an enlarged detail view ofthe femur, tibia, fibula, femoral four-in-one cut guide assembly,proximal tibial cut guide, and a portion of the tibial extension rodassembly of FIG. 137A; FIG. 137C is an anterior view of the femur,tibia, fibula, foot holder assembly, femoral four-in-one cut guideassembly, proximal tibial cut guide, and tibial extension rod assemblyof FIG. 137A; and FIG. 137D is a lateral view of the femur, tibia,fibula, foot holder assembly, femoral four-in-one cut guide assembly,proximal tibial cut guide, and tibial extension rod assembly of FIG.137A;

FIG. 138A is a perspective view of the femoral four-in-one cut guideassembly and the proximal tibial cut guide of FIG. 137A; FIG. 138B isanother perspective view of the femoral four-in-one cut guide assemblyand the proximal tibial cut guide of FIG. 137A from a differentdirection; FIG. 138C is an exploded perspective view of the femoralfour-in-one cut guide assembly and the proximal tibial cut guide of FIG.137A; and FIG. 138D is another exploded perspective view of the femoralfour-in-one cut guide assembly and the proximal tibial cut guide of FIG.137A from a different direction;

FIG. 139A is a front view of the femoral four in one cut guide assemblyof FIG. 138A; FIG. 139B is a cross sectional view of the femoral four inone cut guide assembly of FIG. 139A, taken along section line 139B-139Bof FIG. 139A; FIG. 139C is a cross sectional view of the femoral four inone cut guide assembly of FIG. 139A, taken along section line 139C-139Cof FIG. 139A; FIG. 139D is an exploded perspective view of the femoralfour-in-one cut guide assembly of FIG. 139A; and FIG. 139E is anotherexploded perspective view of the femoral four-in-one cut guide assemblyof FIG. 139A from a different direction;

FIG. 140A is an exploded perspective view of a gear assembly of thefemoral four in one cut guide assembly of FIG. 139A; and FIG. 140B isanother exploded perspective view of the gear assembly of the femoralfour in one cut guide assembly of FIG. 139A from a different direction;

FIG. 141A is a perspective view of the femur, tibia, fibula, foot holderassembly, femoral four-in-one cut guide assembly, proximal tibial cutguide, and tibial extension rod assembly of FIG. 17A with the femoralfour-in-one cut guide assembly and proximal tibial cut guide adjusted tofit the femur and tibia, with bone pins inserted through the femoralfour-in-one cut guide assembly into the femur, with bone pins insertedthrough the proximal tibial cut guide into the tibia; FIG. 141B is anenlarged detail view of the femur, tibia, fibula, foot holder assembly,femoral four-in-one cut guide assembly, proximal tibial cut guide,tibial extension rod assembly, and bone pins of FIG. 141A; FIG. 141C isan enlarged anterior detail view of the femur, tibia, fibula, footholder assembly, femoral four-in-one cut guide assembly, proximal tibialcut guide, tibial extension rod assembly, and bone pins of FIG. 141A;and FIG. 141D is an enlarged lateral detail view of the femur, tibia,fibula, foot holder assembly, femoral four-in-one cut guide assembly,proximal tibial cut guide, tibial extension rod assembly, and bone pinsof FIG. 141A;

FIG. 142 is a perspective view of the femur, tibia, fibula, femoralfour-in-one cut guide assembly, proximal tibial cut guide, a portion ofthe tibial extension rod assembly, and bone pins of FIG. 141A aftermaking anterior and posterior femoral resections, anterior and posteriorchamfer cuts, and a proximal tibial resection;

FIG. 143 is a perspective view of the femur, tibia, and fibula with theanterior, distal, and posterior femoral resections, the anterior andposterior femoral chamfer cuts, and the proximal tibial resection withthe femoral four-in-one cut guide assembly, proximal tibial cut guide,tibial extension rod assembly, and bone pins removed;

FIG. 144 is an isometric view of a knee joint with implanted femoralcomponent, tibial component, articular insert, and patellar component,the patellar component shown exploded from the patella for clarity;

FIG. 145 is a perspective view of a femur, tibia, and fibula withanother femoral pin guide assembly and another distal femoral cut guidecoupled to the distal femur; and

FIG. 146A is an exploded perspective view of the femoral pin guideassembly and distal femoral cut guide of FIG. 145; and FIG. 146B isanother exploded perspective view of the femoral pin guide assembly anddistal femoral cut guide of FIG. 145 from a different direction.

DETAILED DESCRIPTION

Exemplary embodiments of the technology will be best understood byreference to the drawings, wherein like parts are designated by likenumerals throughout. It will be readily understood that the componentsof the system, as generally described and illustrated in the figuresherein, could be arranged and designed in a wide variety of differentconfigurations. Thus, the following more detailed description of theembodiments of the apparatus, system, and method is not intended tolimit the scope of the invention, as claimed in this or any otherapplication claiming priority to this application, but is merelyrepresentative of exemplary embodiments of the technology.

The phrases “connected to,” “coupled to” and “in communication with”refer to any form of interaction between two or more entities, includingmechanical, electrical, magnetic, electromagnetic, fluid, and thermalinteraction. Two components may be functionally coupled to each othereven though they are not in direct contact with each other. The term“abutting” refers to items that are in direct physical contact with eachother, although the items may not necessarily be attached together. Thephrase “fluid communication” refers to two features that are connectedsuch that a fluid within one feature is able to pass into the otherfeature.

The word “exemplary” is used herein to mean “serving as an example,instance, or illustration.” Any embodiment described herein as“exemplary” is not necessarily to be construed as preferred oradvantageous over other embodiments. While the various aspects of theembodiments are presented in drawings, the drawings are not necessarilydrawn to scale unless specifically indicated.

Standard medical planes of reference and descriptive terminology areemployed in this specification. A sagittal plane divides a body intoright and left portions. A mid-sagittal plane divides the body intobilaterally symmetric right and left halves. A coronal plane divides abody into anterior and posterior portions. A transverse plane divides abody into superior and inferior portions. Anterior means toward thefront of the body. Posterior means toward the back of the body. Superiormeans toward the head. Inferior means toward the feet. Medial meanstoward the midline of the body. Lateral means away from the midline ofthe body. Axial means toward a central axis of the body. Abaxial meansaway from a central axis of the body. Ipsilateral means on the same sideof the body. Contralateral means on the opposite side of the body. Thesedescriptive terms may be applied to an animate or inanimate body.

Standard terminology related to knee arthroplasty is employed in thisspecification. Varus means deviation of the distal part of the leg belowthe knee inward, resulting in a bowlegged appearance. Valgus meansdeviation of the distal part of the leg below the knee outward,resulting in a knock-kneed appearance.

ABBREVIATIONS AND NOMENCLATURE

TKAI Total Knee Arthroplasty Instruments, Instrumentation

I Instruments, Instrumentation, or the like

AL Alignment

Fe Femur, Femoral, or Femur-related

Ti Tibia, Tibial, or Tibia-related

EG Extension Gap

FG Flexion Gap

FR Femoral Rotation

TS Tibial Slope

PS Posterior Stabilized

CR Cruciate Retaining

Kn Knee

AIS Anterior Iliac Spine

FeHe Femoral Head

IM Intramedullary

EM Extramedullary

DAFe Distal Anterior Femur

Traditional TKAI utilizes IM I to determine proper distal femur saw cutalignment, and EM I to align the saw cut for the proximal tibia.Therefore it is acceptable to prepare the distal femur separate from theproximal tibia. There exists no conjoined effort to cut the distal femurand the proximal tibia as the single lower extremity body part whichconstitutes the knee joint.

This contemporary instrumentation process violates the principlesestablished by Insall in the 1970s. (Insall, John N. Surgery of theKnee. New York: Churchill Livingstone, 1984. Pages 631-365. Entire bookincorporated by reference in its entirety.) Popular TKAI teaches thisinexact IM I process because it is simpler to teach, understand andutilize by most surgeons. This contradiction is best illustrated byexamining the long time relationship of Zimmer, Inc. and one of itspremier consultants, Dr. Bob Booth (Philadelphia). Dr. Boothsuccessfully and famously performs exact TKAI utilizing his mentor's(Dr. Insall's) principles. However, Zimmer does not commercialize Dr.Booth's instruments and techniques because the technique proves tootechnically difficult for most surgeons.

This disclosure teaches bony and soft tissue preparation of the kneejoint utilizing instruments and techniques consistent with proven TKAIprinciples.

Technique

A longitudinal incision 150 is made from proximal to distal with its midpoint over the anterior knee. A medial arthrotomy is performed instandard fashion. The patella 112 is everted and dislocated laterally asthe knee is flexed to 90 degrees. The medial and lateral supportingligaments of the knee are balanced as needed.

The proximal tibia 106 is resected at a right angle to the long axis ofthe tibia 104, removing approximately 6 mm to 10 mm of bone (intraditional fashion utilizing a tibial cut guide referencing theanterior tibial spine). However, this may be a provisional resectionthat removes 3 mm to 5 mm of bone to increase the working space insidethe knee joint.

The lower extremity (and knee) is now positioned in full extension (0degrees flexion). The full extension of the knee relaxes the extensormechanism. The suprapatellar fat pad 116 is elevated from the anteriordistal femur 102 with a small periosteal elevator 154 (elevating the fatlayer from the anterior femur only—leaving the fat pad attached medialand lateral on the femur).

An instrument is now inserted, from distal to proximal, externally alongthe distal anterior femoral cortex under the suprapatellar fat pad 116.This instrument somewhat resembles a bone plate, having a (longitudinal)distal to proximal length longer than its medial to lateral length(width). This instrument is referred to as a base 10. Rising from thedistal end of this unattached plate, residing on the anterior cortex ofthe distal femur 102, is an element containing a series of stackeddirectional holes 14, 16, 18 which align themselves with each axis ofeach hole pointing (proximal) toward the head 118 of the femur 100. Theaxis of each of these directional holes is 5 degrees valgus to thedistal anterior femoral cortical plate or base 10, previously described.This 5 degree divergence angle varies in absolute direction (relative tomid line of the body) depending upon right or left knee undergoing thissurgery.

In a design, a “hinged” rod is attached, through two of the longitudinalstacked holes so as to align the direction of this rod in the directionof the head 118 of the femur. The “hinged” rod is referred to as analignment rod 156. The proximal end of the rod, once deployed, will bepositioned over the mid portion of the head 118 of the femur, andpreferably directly over the center 120 of the femoral head 118. Thisimportant reference point is determined to be 1) two finger breadthsmedial to the anterior superior iliac spine or, much better, 2)determined by fluoroscopy, radiographs, C-arm, or the like.

The significance of this reference rod 156 is 1) its attachment as partof the femoral “plate” or base 10 residing on the anterior surface ofthe distal femur. The medial/lateral position of the proximal end of therod can be changed by simply and minimally moving the proximal end ofthe femoral “plate” medially (thus increasing the valgus of the distalfemoral cut) or laterally (increasing the varus) to the midline of thedistal anterior femoral cortex. Preferably, the distal end of the rod156 is attached to the base 10 so that the rod passes directly over themedial/lateral center of the distal femur, and the proximal end of therod 156 is moved medial/lateral until the rod passes directly over thecenter 120 of the femoral head 118.

Once alignment is obtained, 2 screws are driven into slots in the distalend of the femoral “plate” or base 10, in order to secure alignment.These 2 screws may be placed outside of the cutting path for theanterior femoral resection 214 so that the cut can occur without hittingthe screws.

A parallel handle 21 is attached to the distal femur cortical “plate”which attaches these two parallel elements distally (but notproximally), and is anterior and separate to the soft tissues of thedistal thigh. This parallel “plate” handle 21 permits compression to beapplied to the distal femur cortical “plate” or base 10 by the surgeonin order to prevent movement (medial or lateral) of the plate from thedesired alignment position (with respect to femoral head 118). Small,sharp “cleats” may be included on the bone-facing surface of the base 10to increase friction contact of the “plate” to the distal anteriorfemoral bone.

Once femoral alignment is secured, the “hinged” rod is moved from(proximal) reference to the hip, to distal reference of the lowerextremity, i.e. the anterior tibial spine or crest, ankle, and/or secondtoe of the foot. This mechanical connection of 1) alignment of the femur100 to the 2) alignment of the tibia 104—through rotation of the“hinged” rod 156 from proximal extremity to distal extremity (while theknee remains unmoved and in full extension) permits direct alignment ofthe proximal extremity (femur 100) with the distal extremity (leg ortibia 104) along the mechanical axis 202 of the leg.

Now, the ankle/foot region of the lower extremity can simply be moved(lateral or medial) under the distal end of the “hinged” rod 156 toalign the entire lower extremity (hip, knee, ankle) in an exact straightline along the mechanical axis 202 of the leg.

The “hinge” aspect of the rod 156 permits proximal alignment referencingthe femoral head 118 without being adversely affected by obesity (therod angles superiorly over a large mid section without compromisingalignment with the femoral head 118).

The “hinged” rod 156 now rotated distally and placed exactly parallelwith the lower extremity (through an articulation at the hinge point)(referencing the plane of the distal anterior femoral cortex), can allowproper attention and calibration for the (final) angle of cut for theproximal tibial cut (previously rough cut).

This means that the desired posterior slope of the tibial cut can now bereferenced off of the exact alignment of the entire length of the lowerextremity, through reference to the distal anterior femoral cortexmaking the distally positioned “hinged” rod parallel to the distalanterior femoral cortex by a short extension of the deployed “hinged”rod extending proximally parallel to the femoral cortex and finallyreaching distally until referencing the ankle or 2nd toe of the foot.

Cutting guides for the distal femur and (simultaneously) proximal tibiaare hung from the deployed “hinged rod” 156. While the “hinged” rod isoverlying the entire tibia 104, the knee joint is distracted until thecollateral ligaments of the knee are “very” taut (knee still in fullextension) and the center of the ankle is under the distal rod 156. Onceproperly and fully distracted and aligned, a four point drill guide(attached at a right angle from the “hinged” rod) is positioned anteriorto the knee joint.

The midpoint of this four point drill guide is positioned at the naturaljoint line. Now, each of the four points of the drill guide (positionedabout 20+ mm apart—equal to the sum width [thickness] of the intendedtibial and femoral prostheses—in extension) are utilized to drill holes(2 each and [all] parallel) in the distal femur and the proximal tibia.Extended, shouldered studs are now placed in each of the drill holes inanticipation of saw guides being positioned by matching receiving holesin the cut plates (one for the distal femur and the other for theproximal tibia).

The distraction device is relaxed and removed from the knee. The cutguides are placed over the shouldered studs. The knee is now flexed (the“hinged” rod elevated and drawn proximally over the femur) and each ofthe two cuts are now made, aligned and properly angled (proximal tibia)by the two cut guides—femur and tibia.

The “hinged rod” attachment to the riser (on the femoral “plate”) is nowadvanced distally by extension through the two stacked holes in theriser, so to match the end of the cut femur. The knee is flexed to 90degrees. The “hinged” rod is now deployed distally and allowed to flexto 90 degrees at its riser hinge. At 90 degrees flexion the rod will nowcross the cut surface of the femur and parallel the anterior spine ofthe tibia.

To adjust for femoral rotation, a technique is now employed. The“hinged” rod is made parallel to Whiteside's line (middle of anteriorand distal femur extending through middle of cut surface of femur [fromthe bottom of the trochlear groove to the top of the intercondylar notch(trochlear notch), at right angles to the epicondylar axis, which is aline between the most prominent points of the medial and lateralepicondyles, or a line connecting the lateral epicondylar prominence andthe medial sulcus of the medial epicondyle]), and then the femuradjusted on the tibia so that Whiteside's line and the anterior spine ofthe tibia are in perfect alignment.

A multi-cut guide is now deployed with a right angle rod attachmentwithin the femoral anterior cortex “plate”. This rod extension attachedto the top of the multi-cut femoral guide will permit (for the firsttime) perfect reference to cutting the anterior and distal femur—byallowing the anterior cut slot to aim directly, proximal, to the base ofthe femoral “plate”. The guide will allow anterior and posterioradjustment of up to 2 mm to allow surgeons to (mildly) notch the femur,or even rise anterior to the anterior cortex—the choice is made by thesurgeon depending on his interest in the sight of the posterior femoralcut (more or less bone posteriorly).

As discussed in the above paragraphs, femoral rotation is adjustedrelative to Whiteside's line and the tibial cut (right angle to it) andthen the multi-cut guide is pinned to the distal femur, and all chamfercuts and anterior and posterior cuts are thus made, directly related toand reference to, the companion member of the knee joint.

Instruments

Base 10 (datum) (FIG. 1) includes trunnion 12 and screw holes 14, 16,18.

The base 10 may be modified so that one (lateral, medial, or posterior)side of the base registers on an anatomic ridge or other structure ordetail of the distal anterior femur. More than one (lateral, medial, orposterior) side of the base may be modified to register on anatomicstructures or details of the distal anterior femur. The anatomicstructures or details may be protruding features, such as ridges, orrecessed features, such as sulci, fossae, grooves, or other depressedfeatures.

Drill guide assembly 20 (FIGS. 2-3) includes handle 21, socket end 22,drill guide 24, handle 26, and tube 28.

Cut guide assembly 30 (FIGS. 4-6) includes pivot block 31, arm 32, andanterior femoral cut guide 34. The anterior femoral cut guide 34includes cut slot 36 aligned with posterior surface 38 of base 10 sothat anterior femoral resection 214 is flush with the distal anteriorfemoral cortical surface on which the base is mounted. This means thatthe posterior surface 38, cut slot 36, and the anterior femoralresection 214 all lie in a common plane. The cut guide assembly 30 alsoincludes posterior femoral cut guide 40; linked to anterior femoral cutguide 34; adjustable on rails 42 for A/P distance; locked with setscrews 44; sizes may be etched on rails and/or size may be set withfeeler gauges and the actual implant and/or with calipers; The posteriorfemoral cut guide 40 may include optional posterior condylar abutmenttabs 46 or optional pin/screw fixation holes 47. The cut guide assembly30 also includes proximal tibial cut guide 48, which mounts to theposterior femoral cut guide 40 and may be available in various sizes tomatch measured flexion gap. The proximal tibial cut guide 48 may mountto the posterior femoral cut guide 40 via dovetail engagement 50, withan optional locking screw. The proximal tibial cut guide 48 may includeoptional pin/screw fixation holes 52.

Anatomy

FIG. 7: femur 100, distal femur 102, tibia 104, proximal tibia 106,quadriceps muscle 108, patellar ligament 110, patella 112, patellartendon 114, and suprapatellar fat pad 116. FIG. 8: femoral head 118 andcenter 120 of the femoral head 118.

FIG. 18: femoral shaft axis 200, mechanical axis 202 of the leg, angle204 between femoral shaft axis 200 and mechanical axis 202 of the leg,distal femoral resection 206, knee joint line 208, proximal tibialresection 210.

FIG. 19: patellar resection 212, anterior femoral resection 214,anterior femoral chamfer cut 216, posterior femoral chamfer cut 218,posterior femoral resection 220, angle 222 between knee joint line 208and proximal tibial resection 210.

FIG. 20: transverse axis 224 of the knee (may also be the axis aboutwhich the knee flexes and extends), anterior-posterior axis 226 of theknee (may also be the axis about which the knee goes into varus andvalgus), superior-inferior translation 228 along the mechanical axis 202of the leg, medial-lateral translation 230 along the transverse axis 224of the knee, anterior-posterior translation 232 along theanterior-posterior axis 226 of the knee, axial rotation 234 about themechanical axis 202 of the leg, rotation 236 about the transverse axis224 of the knee (also known as flexion and extension), rotation 238about the anterior-posterior axis 226 of the knee (also known asvarus-valgus rotation).

Method

Mounting the base 10 to the distal anterior femoral cortex (FIGS. 8-10)may include the steps of making an incision 150, everting the patella112, resecting the distal margin 152 of the fat pad 116, bluntdissection such as with an elevator 154 under the fat pad along themidline of the femoral shaft, inserting the base 10 under fat pad 116with the base 10 aligned with the femoral shaft and centered in themedial/lateral width of the distal femur (epicondylar width), usingdrill guide 20 to drill two holes through base 10 into femur 100,drilling proximal hole through muscle and fat pad, tapping ifdesired/necessary, and anchoring base to femur with screws.

Aligning the pivot block 31 with the mechanical axis 202 of the leg(FIG. 10) may include the steps of using the alignment rod 156 andlocking the pivot block 31. With the pivot block 31 unlocked so that itis free to rotate, the alignment rod 156 is positioned over the femoralhead 118 and moved medial/lateral until the rod passes directly over thefemoral head center 120. The pivot block 31 is then locked to preventany further medial/lateral rotation. However, the alignment rod 156 isstill free to swing between proximal and distal positions.

Making the femoral cuts (FIGS. 11-13) may include the steps of adjustingthe femoral cut guides 34, 40 to match A/P femoral dimension 158 oftemplated femur size, flexing knee to 90 degrees, mounting arm 32 andfemoral cut guides 34, 40 to pivot block 31, sliding cut guides intocontact with distal femur, optionally adding pins or screws to secureposterior cut block to femur, and making anterior and posterior femoralcuts, e.g. with a powered oscillating saw or other cutting tool.

Making the tibial cut (FIGS. 14-17) may include the steps of determiningflexion gap with spacers (as is known in the art) to produce desiredtension in flexion, selecting proximal tibial cut guide 48 to matchmeasured gap, sliding femoral cut guides 34, 40 away from femur,mounting proximal tibial cut guide 48 to posterior femoral cut guide 40,sliding cut guides 40, 48 into contact with proximal tibia, tensioningjoint (wedge 160 FIG. 16 or screw 162 through arm 32 FIG. 17),optionally adding pins or screws to secure proximal tibial cut block totibia, and making proximal tibial cut.

Adjustments and remaining cuts may be made as known in the art, forexample flexion and extension gap adjustments via soft tissue release orrecutting bone, marginal osteophyte removal, distal femoral cut, andchamfer cuts.

Referring to FIGS. 21A-23B, another instrument system 300 is shown. Thisinstrument system 300 is designed so that bone pins may be placed in thedistal femur 102 and proximal tibia 106 while the knee joint is in fullextension and maximally distracted, while referencing the distalanterior femoral cortex, and while the leg (femoral head center 120,distal femur 102, proximal tibia 106, and ankle/second toe/anteriortibial spine or crest) is properly aligned with the mechanical axis 202of the leg. The bone pins serve as mounting fixtures for subsequentinstruments, such as cut guides. The system 300 includes apparatus forreferencing Whiteside's line while the distal femoral condyles areintact, before any femoral resection occurs, and locking this referenceinto the apparatus to guide later surgical steps. This design hasadvantages for, and may be used for, many types of knee arthroplasty,such as bicompartmental or bicondylar knee arthroplasty where theprosthetic components replace and extend across the medial and lateralcompartments (with or without a prosthetic patellar component), orunicompartmental or unicondylar knee arthroplasty where the prostheticcomponents replace the medial or lateral compartment or a singlecondyle. This design may also be advantageous when replacing the medialand lateral compartments with independent medial and lateralunicompartmental prosthetic components, for example, to spare theanterior cruciate ligament (ACL).

The instrument system 300 may include a base 302, a femoral riser 304(also known as a handle), a femoral extension rod 306, a tapered plugassembly 308, a tibial-femoral pin guide 310, a tibial riser 312, and atibial extension rod 313. The instrument system 300 is shown with fivetapered plug assemblies 308 (FIG. 21B) and a three-piece telescopingtibial extension rod 313 including a tibial outer extension rod 314, afirst tibial inner extension rod 316, and a second tibial innerextension rod 318. The instrument system 300 may also include additionalcomponents as described below for FIGS. 21A-46.

Referring to FIGS. 24A-25B, the femoral riser 304, or handle, may berigidly coupled to the base 302 in one or more orientations. FIGS.24A-25B illustrate an arrangement in which the femoral riser 304 may becoupled to the base 302 in two orientations. The base 302 includes twoslots 344, 346 recessed in a top surface 348 of the base. An acute angle345 is formed between the slots 344, 346. The magnitude of the angle 345may be related to the angle 204 between the femoral shaft axis 200,represented by a longitudinal axis 301 of the base 302, and themechanical axis 202 of the leg (FIG. 18), represented by a longitudinalaxis 311 of the femoral riser 304. In the illustrated example, angle 345may be two times angle 204. The femoral riser 304 includes a ridge 350,or tab, which is received in one of the slots 344, 346 when the femoralriser 304 is coupled to the base 302. The base 302 also includes threeholes 352, 354, 356 which are arranged adjacent to the ends of the slots344, 346. In this example, three holes are sufficient since the slotsintersect on the base 302; four holes would be more appropriate if theslots did not intersect on the base 302, and in general the number ofholes varies according to the number and arrangement of slots on thebase. The femoral riser 304 includes two holes 358, 360 which arearranged adjacent to the ends of the ridge 350. When the ridge 350 isinserted in slot 344, a fastener may be inserted through holes 358, 352,and another fastener may be inserted through holes 360, 356. When theridge 350 is inserted in slot 346, a fastener may be inserted throughholes 358, 352, and another fastener may be inserted through holes 360,354.

Referring to FIGS. 25A-26B, the femoral extension rod 306 may bepivotally coupled, or hinged, to the femoral riser 304 by a pin, screw,or other fastener through holes 305, 307. Hinge 309 is shown in FIGS.21B and 23B. The femoral extension rod 306 may remain coupled to thefemoral riser 304 in service. In use, the femoral extension rod 306 isfree to pivot about the hinge 309 to adjust to the patient's anatomy.The femoral extension rod 306 pivots in an anterior-posterior directionwhich is generally parallel to the sagittal plane. The femoral extensionrod 306 is constrained against pivoting in a medial-lateral directionwhich is generally parallel to the coronal plane.

Referring to FIGS. 25A, 25B, 28A, and 28B, the tibial-femoral pin guide310 may be rigidly coupled to the femoral riser 304 by engaging a tab362 of the femoral riser 304 (FIG. 25A) in a slot 364 of thetibial-femoral pin guide 310 (FIG. 28B) and inserting fasteners throughholes 366, 370 and holes 368, 372. Alternatively, the tibial-femoral pinguide 310 may be coupled to the femoral riser 304 by engaging the tab362 in the slot 364 without using fasteners.

Referring to FIGS. 27A-27C, the tapered plug assembly 308 may include atapered plug 320, a cap 322, and a lock 324. The tapered plug assembly308 may closely encircle the bone pin with minimal clearance, justenough clearance to permit the bone pin to be rotationally driventhrough the tapered plug assembly 308 while permitting little to noangular deviation of the bone pin. In an alternate embodiment, thetapered plug assembly 308 may move between a closed configuration and anopen configuration. In the closed configuration, the tapered plugassembly 308 may fit closely around the bone pin. In the openconfiguration, the tapered plug assembly may fit loosely around the bonepin. The inside diameter through the tapered plug assembly 308 may belarger in the open configuration than in the closed configuration.

Referring to FIGS. 27A-28B, each tapered plug assembly 308 is receivedin a hole 374 of the tibial-femoral pin guide 310 so that the wide endof the tapered plug 320 is in the hole 374, the narrow end of thetapered plug 320 extends beside a boss 376 of the tibial-femoral pinguide 310, and an arm 325 of the lock 324 is adjacent to the boss 376.The hole 374 may have an internal taper corresponding to the externaltaper of the tapered plug 320. The tapered plug assembly 308 may becaptive to the tibial-femoral pin guide 310 in service. When the arm 325is over the boss 376 (FIGS. 21B, 22B) in a locked configuration, thetapered plug assembly 308 is held in tight engagement in the hole 374;when the arm 325 is rotated away from the boss 376 in an unlockedconfiguration, the tapered plug assembly 308 is free to drop down so asto fit more loosely in the hole 374. In the alternate embodiment, whenthe arm 325 is over the boss 376, the tapered plug assembly 308 is inthe closed configuration; when the arm 325 is rotated away from the boss376, the tapered plug assembly 308 is in the open configuration. Thelocked or closed configurations of the tapered plug assembly 308 provideprecise, close-fitting holes while the bone pins are being driven, sothat the pins are accurately positioned, mutually parallel to eachother, and all perpendicular to the mechanical axis 202 of the leg. Theunlocked or open configurations of the tapered plug assembly 308 providea looser fit after the bone pins have been driven, so that thetibial-femoral pin guide 310 can be removed more easily. The unlockedconfiguration provides a looser fit between the hole 374 and the taperedplug 320, while the open configuration provides a looser fit between thetapered plug 320 and the bone pin.

Referring to FIGS. 28A-29B, the tibial riser 312 may be rigidly coupledto the tibial-femoral pin guide 310 by inserting boss 378 of thetibial-femoral pin guide 310 into notch 380 of the tibial riser 312 andinserting a fastener through holes 382, 384. Alternately, the tibialriser 312 may be permanently rigidly coupled to the tibial-femoral pinguide.

Referring to FIGS. 29A-30B, the tibial outer extension rod 314 may bepermanently rigidly coupled to the tibial riser 312 by welding tabs 386of the tibial outer extension rod 314 to a corresponding fitting 388 ofthe tibial riser 312. Any tibial extension rod may be coupled to thetibial riser 312 in the same way. Alternately, tibial outer extensionrod 314 may be removably or hingedly coupled to the tibial riser 312.

Referring to FIGS. 30A-31B, the first tibial inner extension rod 316 maybe telescopically coupled to the tibial outer extension rod 314 byinserting the first tibial inner extension rod 316 into a centrallongitudinal hole 390 of the tibial outer extension rod 314 andinserting a fastener through a slot 392 of the tibial outer extensionrod 314 and into a hole 394 of the first tibial inner extension rod 316,so that the tibial inner extension rod 316 is slidable within, andcaptive to, the tibial outer extension rod 314. The fastener may beremovable so that the first tibial inner extension rod 316 may beremoved from the tibial outer extension rod 314.

Referring to FIGS. 31A-32B, second tibial inner extension rod 318 may bepivotally coupled to the first tibial inner extension rod 316 byinserting a fastener through holes 396, 398 to form a hinge 317 (FIGS.21A and 23A). The second tibial inner extension rod 318 may remaincoupled to the first tibial inner extension rod 316 in service. In use,the second tibial inner extension rod 318 is free to pivot about thehinge 317 to adjust to the patient's anatomy.

Prior to use, the base 302 and the femoral riser 304, with femoralextension rod 306, may be rigidly coupled together in an orientationappropriate to the surgical conditions, i.e., in a left orientation fora left knee, or in a particular angular orientation based uponpre-operative planning. Tapered plug assemblies 308 may be installed inthe holes 374 of the tibial-femoral pin guide 310, and moved to thelocked or closed configuration. The tibial riser 312, with tibialextension rod(s) 313, 314, 316, 318, may be rigidly coupled to thetibial-femoral pin guide 310. The tibial-femoral pin guide 310, withattached tibial riser 312 and tibial extension rod(s), may be rigidlycoupled to the femoral riser 304.

Alternatively, the base 302, femoral riser 304, and femoral extensionrod 306 may be coupled together as a femoral assembly, and thetibial-femoral pin guide 310, tapered plug assemblies 308 (locked orclosed), tibial riser 312, and tibial extension rod(s) 313, 314, 316,318 may be coupled together as a tibial assembly. Users may find thatthe femoral assembly is easier to manipulate without the tibial assemblyattached, particularly when insinuating the base 302 between thesuprapatellar fat pad 116 and the anterior distal femoral cortex. Usersmay prefer to couple the tibial assembly to the femoral assemblyimmediately before distracting the knee joint and aligning the tibia.

The base 302 may be inserted under the suprapatellar fat pad 116 andagainst the distal anterior femoral cortex in the manner describedpreviously. The femoral riser 304 may rest against or within thetrochlear groove. The femoral extension rod 306 may rest against theanterior aspect of the patient's thigh and hip. The proximal free end ofthe femoral extension rod 306 may be shifted medial-lateral until thefemoral extension rod 306 passes over the center 120 of the femoral head118. Proper alignment is achieved when the distal end of the femoralextension rod 306, base 302, and femoral riser 304 are centered in themedial/lateral width of the distal femur 102 while at the same time theproximal end of the femoral extension rod 306 passes over the femoralhead center 120.

Shown later in this application, a target may be used in conjunctionwith the femoral extension rod 306 to precisely and objectively locatethe center 120 of the femoral head 118. A target may be positioned overthe anterior aspect of the patient's hip and/or over the center 120 ofthe femoral head 118 with fluoroscopic, radiographic, or C-arm imaging.Later, when the femoral extension rod 306 is positioned along thepatient's thigh, the proximal free end of the rod 306 may be positionedrelative to the target. The target may be a fork or “goal post,” a ring,a reticle, “cross hairs,” or the like, mounted to the free end of anadjustable arm whose base is stationary. In this application, a targetmay be “over the center of the femoral head” even if the target isactually superior or inferior to the femoral head, so long as thefemoral extension rod passes over the center of the femoral head whenthe rod is aimed at the target. Alternatively, the proximal free end ofthe femoral extension rod 306 may be positioned relative to the anterioriliac crest.

Once the proximal free end of the femoral extension rod 306 ispositioned over the center 120 of the femoral head 118, the base 302 maybe pressed firmly against the distal anterior femoral cortex. Anassistant may press down against the proximal portion of the femoralriser 304 with their palm. Optional spikes 303 (FIG. 24B) or otherfrictional elements may be included on the bone-facing side 349 of thebase 302 to further stabilize the base against the bone. At this point,the base 302, the femoral riser 304, and the femoral extension rod 306are aligned with the mechanical axis 202 of the leg (at least where itextends through the femur).

Certain ligaments may be at least partially released, or cut, at thisstage or at another time in the procedure. For example, one or both ofthe cruciate ligaments may be cut at this stage in accordance with thedesign of the implants which will be used. One or both of the collateralligaments may be released. At this stage, a provisional proximal tibialresection of about 3 mm to 5 mm to 6 mm (within surgical tolerances) maybe made. The provisional proximal tibial resection increases the jointspace so that a distractor, spreader, or other instrument may moreeasily fit between the distal femur and proximal (resected) tibia duringa subsequent distraction step, and so that the knee joint (and lowerlimb) is more mobile during a subsequent lower limb positioning step.The provisional proximal tibial resection may also protect the posteriorcruciate ligament (PCL) when a cruciate-retaining (CR) (orcruciate-sparing, CS) implant system is used.

The lower leg may now be distracted to the extent permitted by theexisting ligamentous structures of the knee. A distractor, spreader, orother instrument may be used in the knee joint space to providemechanical advantage. The distractor may indicate the applieddistraction force. Alternatively, an assistant may manually distract thelower limb. As the distraction force is applied, the lower limb may bemoved medial-lateral to align it with the distal free end of the tibialextension rod—in the example shown, the distal free end of extension rod318. The alignment of the proximal free end of the femoral extension rod306 may be monitored at this stage to ensure that it remains alignedover the center 120 of the femoral head 118 as the lower leg is broughtinto alignment with the distal free end of the tibial extension rod 318.The lower leg is properly aligned when the proximal end of the tibialextension rod 313 is centered in the medial/lateral width of theproximal tibia 106 and the distal free end of the tibial extension rod318 is centered over the ankle and/or the second toe of the foot. Thisestablishes the desired tibial varus/valgus rotation.

Once the knee joint is fully distracted, the proximal free end of thefemoral extension rod 306 is positioned over the center 120 of thefemoral head 118, the distal femur 102 and proximal tibia 106 arecentered with respect to the femoral and tibial extension rods 306, 313,and the lower leg is aligned with the distal free end of the tibialextension rod 318, bone pins may be driven through the tapered plugassemblies 308 and the tibial-femoral pin guide 310. In the exampleshown, up to three pins may be driven into the distal femur 102, and upto two pins may be driven into the proximal tibia 106. All of the pinsare parallel to each other and perpendicular to the mechanical axis 202of the leg.

After the bone pins are driven, the tapered plug assemblies 308 may bemoved to the unlocked or open configuration to provide a looser fit sothat the tibial-femoral pin guide 310 can be removed more easily. Thetibial-femoral pin guide 310 may be uncoupled from the femoral riser 304and removed from the surgical site, along with the tapered plugassemblies 308, the tibial riser 312, and the tibial extension rods 313,314, 316, 318. The base 302 may then be pulled distally out from underthe suprapatellar fat pad 116, along with the femoral riser 304 and thefemoral extension rod 306. Only the bone pins remain in the distal femur102 and proximal tibia 106.

Referring to FIGS. 35-41B, a femoral base block assembly 330 may beincluded in the instrument system 300. The femoral base block assembly330 may include a femoral base block 332, a translation bar 334, a knob336, a top component 338, a bottom component 340, and a socket 342. Thetranslation bar 334 includes two parallel shafts 335, 337 which slidewithin holes 339, 341, respectively, of the femoral base block 332.

The femoral base block 332 of the assembly 330 may be placed over thefemoral bone pins after the rest of the components of system 300 havebeen removed and before any resections are made (other than theprovisional tibial resection mentioned above). The femoral base block332 may be oriented so that a tab 333 (FIG. 36B) contacts the distalanterior femoral cortex in or immediately adjacent to the formerlocation of the distal portion of the base 302 (i.e., near the formerlocation of hole 352). The tab 333 therefore contacts the distalanterior femoral cortex in the same plane as the base 302, providingdirect referencing for a subsequent anterior femoral resection 214. Ashort shaft or rod (not shown) may be coupled in the socket 342 so thatthe short shaft extends posteriorly in the intercondylar notch(trochlear notch). The knee may be flexed to facilitate access andvisualization of the intercondylar notch. The short shaft, socket 342,bottom component 340, top component 338, and knob 336 may be rotatedabout a post 400 of the translation bar 334 to align the short shaftwith Whiteside's line. The short shaft may be locked in alignment withWhiteside's line, for example by tightening the knob 336, top component338, bottom component 340, socket 342, or with a locking element (notshown). The femoral base block assembly 330 may then be removed from thefemoral pins and the short shaft may be removed from the socket 342.

Referring to FIGS. 33A-33B, a femoral cut guide 326 may be included inthe instrument system 300. The femoral cut guide 326 may be placed overthe femoral pins, and a saw used through the femoral cut guide to make adistal femoral resection 206.

The femoral base block 332 of the assembly 330 may be replaced over thefemoral pins, and a femoral cutting block or four-in-one cut guide 750(FIGS. 61A and 61B) may be coupled to the socket 342 so that thefour-in-one cut guide rests against the distal femur in proper alignmentwith Whiteside's line due to the pre-set rotational position of the knob336, top component 338, bottom component 340, and socket 342. Thefour-in-one cut guide 750 may guide multiple femoral cuts, such as theanterior femoral resection 214, the anterior femoral chamfer cut 216,the posterior femoral resection 220, and the posterior femoral chamfercut 218. The anterior femoral resection 214 may be precisely alignedwith the distal anterior femoral cortex as a result of the base 302directly referencing the distal anterior femoral cortex and the femoralbase block assembly 330 suspending the four-in-one cut guide 750 withits anterior resection slot 756 at the same level. The tab 333 of thefemoral base block 332 contacts the distal anterior femoral cortex asdid the base 302 to provide accurate positioning of the anteriorresection slot of the femoral cutting block coupled to the femoral baseblock assembly 330.

Referring to FIGS. 34A-34B, a tibial cut guide 328 may be included inthe instrument system 300. The tibial cut guide 328 may be placed overthe tibial pins, and a saw used through the tibial cut guide to make aproximal tibial resection 210. The proximal tibial resection 210 may bemade at the same time as, or immediately after, the distal femoralresection 206; it may also be made after all femoral resections arecomplete. The tibial cut guide 328 may be designed to produce a tibialresection 210 that is perpendicular to the mechanical axis 202 of theleg, which may be referred to as a zero degree resection. The tibial cutguide 328 may be designed to produce a tibial resection 210 that formsan angle other than 90 degrees with the mechanical axis. For example,the tibial cut guide 328 may produce a tibial resection 210 that slopesposteriorly and inferiorly. A sloping tibial resection 210 may bereferred to by its angle relative to a perpendicular resection. Forexample, a six degree tibial resection slopes from anterior-superior toposterior-inferior, making a six degree angle with a theoreticalperpendicular resection. Multiple posterior resection angles arecontemplated herein, for example, zero degrees and six degrees.

Referring to FIGS. 42A-46, another translation bar 404, a slide 406, acut guide 408, and a condyle probe 410 may all be substituted into thefemoral base block assembly 330 of FIG. 35 instead of the translationbar 334, knob 336, top component 338, bottom component 340, and socket342. The translation bar 404, slide 406, cut guide 408, and condyleprobe 410 may be referred to collectively as an alternatetranslation/cut guide assembly 402. The alternate translation/cut guideassembly 402 may be applicable to bicompartmental or bicondylar kneearthroplasty, or unicompartmental or unicondylar knee arthroplasty. Thealternate translation/cut guide assembly 402 may be particularlyapplicable to unicompartmental or unicondylar knee arthroplasty due tothe X-Y translation provided by the double dovetail slide design, whichprovides anterior-posterior and medial-lateral sliding adjustment inaddition to the superior-inferior sliding adjustment provided by thetranslation bar 404. The cut guide 408 includes slots for distal femoraland proximal tibial cuts. The condyle probe 410 may be used to centerthe cut guide 408 across the joint space.

Referring to FIGS. 47A-49B, yet another instrument system 500 is shown.This instrument system is designed to be used while the knee joint is infull extension and maximally distracted, while referencing the distalanterior femoral cortex, and while the leg is properly aligned with themechanical axis 202 of the leg. The femoral head center 120, distalfemur 102, proximal tibia 106, and ankle/second toe/anterior tibialcrest or spine are all simultaneously aligned with the mechanical axis202. The system 500 includes apparatus for referencing Whiteside's linewhile the distal femoral condyles are intact, before any femoralresection occurs, and locking this reference into the apparatus to guidelater surgical steps.

The instrument system 500 is illustrated with a combination ofcomponents that is similar to those depicted in FIGS. 21A and 21B forinstrument system 300. The instrument system 500 may include a base 502,a femoral riser 504 (also known as a handle), a femoral extension rod506, a tibial connection block 508, and a tibial pin guide 510. Theinstrument system 500 may also include a tibial riser 509 like tibialriser 312, and a tibial extension rod 511 like tibial extension rod 313,alignment rod 156, femoral extension rod 306, or femoral extension rod506. The illustrated tibial extension rod 511 is identical to thefemoral extension rod 506. The instrument system 500 may also includeadditional components as described below for FIGS. 47A-68B. At least thefemoral riser 504, tibial connection block 508, tibial pin guide 510,and, if present, tibial riser 509 may be disposable components moldedfrom polymer materials.

Referring to FIGS. 50A and 50B, the femoral riser 504 is shown coupledto the base 502. A cam 512 is visible coupled to the base 502 in FIG.50B. The femoral riser 504 may include a femoral pin guide 514 and ahandle 516. The femoral pin guide 514 and handle 516 may be rigidlycoupled together in a releasable or permanent manner. The femoral pinguide 514 and handle 516 may be fabricated as a unitary part. Thecoupled femoral riser 504 and base 502 may be analogous to the coupledfemoral riser 304, base 302, and a portion of the tibial-femoral pinguide 310.

Referring to FIGS. 51A and 51B, the base 502 is an elongated plate witha bone contacting surface 518 and an opposite top surface 520. The base502 has a distal portion 522 and a proximal portion 524 which tapers toa proximal tip which is narrower than the distal portion. A longitudinalaxis 503 extends along the length of the base 502 between the distal andproximal portions 522, 524; only a portion of the axis 503 is shown inFIG. 51B for clarity. The base 502 includes a hole 526 through thedistal portion 522. A pocket 528 is recessed into the bone contactingsurface 518 around the hole 526. The pocket 528 may be described as acounterbore around the hole 526. The base 302 includes three oblongholes 530, 532, 534 recessed into the top surface 520. Each hole 530,532, 534 includes a shelf 536 on at least one side wall. The shelves 536are illustrated on the distal side walls of the holes 530, 532, 534 butmay be on the proximal side walls or elsewhere instead. The base 502 mayinclude one or more frictional elements, such as spikes 538 protrudingfrom the bone contacting surface 518.

Referring to FIGS. 51C and 51D, the cam 512 includes a body 540 and aspindle 542 that protrudes from the body. The body 540 has anon-circular cross-sectional profile around the spindle 542 so that asthe cam 512 turns about the spindle, the body can exert (or release) aside force against another object. Thus the body 540 has a lockingportion 546 and an unlocking portion 548 which may be generally oppositethe locking portion, or at least circumferentially spaced apart from thelocking portion. The locking portion 546 extends radially farther fromthe spindle 542 than the unlocking portion 548 does. The body 540 mayinclude a resilient portion 550, which may be between the lockingportion 546 and the unlocking portion 548, or may be associated with thelocking portion 546 as illustrated. The resilient portion 550 ischaracterized by a slot 552 which enables the resilient portion to flexunder load. The spindle 542 is cylindrical and is narrower than the body540. A torque socket 544 is recessed into the body 540 opposite thespindle 542, and concentric with the spindle. The torque socket 544 isillustrated as a hex socket, although a square, cruciate, hexalobular,or other non-circular shape could be substituted.

The cam 512 is coupled to the base 502 by inserting the spindle 542 intothe hole 526 and inserting the body 540 into the pocket 528. The cam 512may be captive to the base 502, at least during use. The cam 512 may beremovable from the base 502.

Referring to FIGS. 52A and 52B, the femoral pin guide 514 is a roughlytriangular plate with a bone facing surface 562 and an opposite topsurface 564. The femoral pin guide 514 has a distal portion 566 and aproximal portion 568 which tapers to a proximal tip which is narrowerthan the distal portion. A stalk 570 protrudes from the top surface 564.A first hole 572 extends through the stalk 570 in a proximal-distaldirection and a second, smaller diameter, hole 574 extends through thestalk parallel to the first hole 572 and farther from the top surface564. The stalk 570 terminates in a narrow tab 576 which has a hole 578that is transverse to the holes 572, 574. The femoral pin guide 514 isillustrated with several holes 580, 582 which receive bone pins. Twoproximal holes 580 are shown and twelve distal holes 582 are shown,although any number of holes may be provided. The left and right holes580 converge together as they approach the bone facing surface 562. Theleft group and the right group of holes 582 also converge together asthey approach the bone facing surface 562. This is best appreciated inFIGS. 73 and 77. The left group and the right group of holes 582 mayinclude individual holes 582 that are spaced apart widely enough in themedial-lateral direction that all five femoral resections 206, 214, 216,218, 220 may be cut, and a femoral trial component coupled to theresected distal femur, while the base 502 and femoral pin guide 514remain secured to the femur 100. These widely spaced holes 582 may belocated outboard of the mounting holes 584 so that bone pins driventhrough the widely spaced holes 582 penetrate the epicondyles. Brieflyreferring to FIGS. 52A and 80A, a first widely spaced hole 582 may bemedial to the medial mounting hole 584 and a second widely spaced hole582 may be lateral to the lateral mounting hole 584, “medial” and“lateral” used with reference to the patient's body. The femoral pinguide 514 may be widened to support the widely spaced holes 582.Advantageously, this detail enables the knee joint, with trialcomponents, to be taken through a range of motion with the femoral pinguide 514 secured to the femur 100. Femoral alignment to the mechanicalaxis 202 of the leg is thus preserved until the knee is proven tofunction satisfactorily with trial components. The femoral pin guide 514includes two mounting holes 584 in the distal medial and lateralcorners. A hole (not shown) may be present centered between the mountingholes 584. The femoral pin guide 514 includes a first post 586 and asecond post 588 protruding from the bone facing surface 562. Each post586, 588 includes an oblong tab 590 on at least one side of the free endof the post. The tabs 590 are shown on the distal sides of the posts586, 588 but may be on the proximal sides or elsewhere instead to matchthe oblong holes 530, 532, 534 of the base 502. The femoral pin guide514 may be analogous to a proximal portion of the tibial-femoral pinguide 310.

Referring to FIGS. 53A and 53B, the handle 516 is an elongated curvedpart with a distal portion 592 and a proximal portion 594. The distalportion 592 includes a slot 596. A hole 598 extends through the handle516 across the slot 596. The proximal portion 594 includes a slot 600. Ahole 602 extends through the handle 516 across the slot 600.

The handle 516 is coupled to the femoral pin guide 514 by inserting thetab 576 into the slot 596 so that the proximal portion 568 and theproximal portion 594 extend in the same direction, aligning the hole 598with the hole 578, and inserting a fastener through the holes 598, 578.Referring briefly to FIGS. 48B and 80B, the handle 516 extends along themechanical axis 202 of the leg in use, at least in an anterior view.Therefore, the handle 516 may be said to have a longitudinal axis 517that extends in a proximal-distal direction.

The femoral riser 504 may be rigidly coupled to the base 502 in one ormore orientations. In the example shown, the femoral riser 504 may becoupled to the base 502 in two orientations corresponding to a left orright knee with a fixed angle 204. The first post 586 is received inoblong hole 530 and the second post 588 is received in oblong hole 532or oblong hole 534. Then the cam 512 may be rotated within the pocket528 until the resilient portion 550 contacts the first post 586, pushingthe tabs 590 to engage the shelves 536 to lock the base 502 to thefemoral riser 504. Additional orientations may be provided by providingadditional oblong holes, like holes 532, 534, to receive the second post588. For example, an array of four oblong holes may be provided toprovide a choice of left or right knee and small or large angle 204between the mechanical axis 202, represented by the axis 517 of thehandle 516, and the femoral shaft axis 200, represented by the axis 503of the base 502. It is contemplated that the angle 204 may be adjustablebetween 4 degrees and 7 degrees by providing an array of oblong holes toreceive the second post 588. Briefly referring to FIGS. 49B and 77, whenthe femoral riser 504 is coupled to the base 502, the bone facingsurface 562 of the femoral pin guide 514 is spaced apart anteriorly withrespect to the bone contacting surface 518 of the base. This spacing isadvantageous because it complements the natural anatomy of the intactdistal femur by avoiding contact with the anterior aspects of thefemoral condyles, and also because it provides room to make the anteriorfemoral resection 214 and anterior femoral chamfer cut 216 with the base502 and femoral riser 504 coupled to the femur 100.

Referring to FIGS. 54A and 54B, the femoral extension rod 506 may be atelescopic assembly including an outer extension rod 604, an innerextension rod 606, a spool 608, a sleeve 610, a ring 612, and aretaining ring 614. The femoral extension rod 506 may alternately be afixed length rod like femoral extension rod 306. The outer extension rod604 is a tubular part with a central longitudinal hole 616 and anexternal groove 618 around one end. One or more ports 620 may pierce theouter extension rod 604. The ports 620 are best seen in FIGS. 48A and49A. The inner extension rod 606 is a cylindrical rod with an externalgroove 622 around one end and a transverse hole 624 through an oppositeend. The inner extension rod 606 may include flats 626 on both sidesaround the hole 624. The spool 608 is a tubular part with a centrallongitudinal hole 628 and an external flange 630 projecting outwardlyaround each end. The sleeve 610 is a tubular part with a centrallongitudinal hole 632 and an external flange 634 projecting outwardlyaround one end. The ring 612 has a central hole 636.

The femoral extension rod 506 may be assembled as follows. The ring 612is permanently fixed to the groove 622 of the inner extension rod 606.The ring 612 and inner extension rod 606 slide into the outer extensionrod 604 so that the ring 612 is pointed toward the same end of theassembly as the groove 618 of the outer extension rod 604. The innerextension rod 606 slides into the sleeve 610, and the sleeve slides intothe outer extension rod 604 so that the flange 634 abuts the end of theouter extension rod 604 opposite the groove 618. The sleeve 610 is fixedto the outer extension rod 604. The ring 612 is too large to passthrough the sleeve 610. The spool 608 slides over the outer extensionrod 604. The retaining ring 614 rests in the groove 618 of the outerextension rod. The retaining ring 614 and the flange 634 are each toolarge to pass through the spool 608.

The assembled femoral extension rod 506 may be coupled to the handle 516by inserting the end of the inner extension rod 606 with the hole 624into the slot 600, aligning the hole 602 with the hole 624, andinserting a fastener through the holes 602, 624 to form a hinge 603(FIGS. 47B and 49B). The femoral extension rod 506 is free to pivotabout the hinge 603. In use, the femoral extension rod 506 pivots in ananterior-posterior direction which is generally parallel to the sagittalplane. The femoral extension rod 506 is constrained against pivoting ina medial-lateral direction which is generally parallel to the coronalplane. The outer extension rod 604 is free to slide (telescope) alongthe inner extension rod 606 at least until the ring 612 abuts the sleeve610, and the spool 608 is free to slide along the outer extension rod atleast between the flange 634 and the retaining ring 614. However, thespool 608 is captive to the outer extension rod 604, which is captive tothe inner extension rod 606. The end of the inner extension rod 606 withthe hole 624 is the distal end of the femoral extension rod 506, and theend of the outer extension rod 604 with the retaining ring 614 is theproximal end of the femoral extension rod.

Referring to FIGS. 55A and 55B, a distal femoral condyle block 638includes a mounting portion 640 and a paddle 642. The mounting portion640 includes a bar 644 with a peg 646 extending from each end of thebar. The pegs 646 are parallel, and in this example they are separatepins which are coupled to the bar 644. However, the pegs 646 may beintegrally formed with the bar 644. The bar 644 includes a planar cutguide surface 648 which faces the pegs 646 and which may extend into oneor more slots 650 beside the pegs. The cut guide surface 648 may beentirely enclosed within a single slot 650 rather than having an openmiddle portion as shown. The slot(s) 650 may be referred to as saw slotsor cut guide slots. The paddle 642 in this example is a generallyrectangular flat plate which is integrally formed with the bar 644 andextends from the bar 644 in the same direction as the pegs 646. Theillustrated distal femoral condyle block 638 is for a left knee, hencethe paddle 642 is positioned to rest on a distal medial femoral condylein use.

The distal femoral condyle block 638 releasably couples to the femoralriser 504. The pegs 646 fit into the mounting holes 584 so that the cutguide surface 648 faces the distal portion 566. There is room to pass asaw blade between the cut guide surface 648 and the distal portion 566to make a distal femoral resection 206; thus a saw slot or cut guideslot is formed between these features. The distal femoral condyle block638 may function as a distal femoral cut guide.

The illustrated distal femoral condyle block 638 is designed so that theproximal surface of the paddle 642 is 9 mm from the distal surface ofthe distal portion 566 when the distal femoral condyle block 638 iscoupled to the femoral riser 504, and so that the cutting slot is formedbetween the cut guide surface 648 and the distal surface of the distalportion 566. However, there are situations where it may be desirable totake more than 9 mm of bone from the distal femoral condyles, forexample in patients with flexion contracture where only the extensiongap requires adjustment so that the knee can be brought to fullextension. Flexion contracture may only be appreciated after an initial9 mm distal femoral resection 206 has been made and the knee joint hasbeen taken through a range of motion with trial components. The system500, as well as the other systems disclosed herein, may be adapted toprovide multiple locations (cutting slot positions) for the distalfemoral resection 206. The distal femoral condyle block 638 may bedesigned so that the proximal surface of the paddle 642 is more than 9mm from the distal surface of the distal portion 566 when the distalfemoral condyle block 638 is coupled to the femoral riser 504.Dimensions between 11 mm and 17 mm are contemplated. This positions thedistal surface of the distal portion 566 sufficiently proximal to thedistal medial femoral condyle so that the distal femoral resection 206may be adjusted (re-cut) to take 2 mm, up to 8 mm, more bone from thedistal femoral condyles, from an initial distal femoral resection 206that is 9 mm proximal to the distal medial femoral condyle. The distalfemoral condyle block 638 may be designed with multiple discrete cuttingslots, the distal-most cutting slot including the cut guide surface 648spaced 9 mm from the proximal surface of the paddle 642, and the moreproximal cutting slots incrementally spaced, for example 2 mm apart; orthe distal femoral condyle block 638 may include a movable cutting slotthat can be adjusted in the proximal-distal direction to remove 9 mm to17 mm of bone from the distal femoral condyles; or a set of distalfemoral condyle blocks 638 may be provided, each with a different distalfemoral resection depth; or the distal femoral condyle block 638 may beused only to initially position the base 502 and the femoral riser 504,and one or more separate distal femoral cut blocks (not shown) may beprovided, that releasably couple to the femoral riser 504 in the sameway as the distal femoral condyle block 638. Of course the 17 mm exampledimension may be larger or smaller as a matter of design choice. Thisparagraph further supports the advantages of keeping the base 502 andthe femoral pin guide 514 secured to the femur 100 while the knee jointis taken through a range of motion with trial components. The distalfemoral resection 206 may be adjusted (re-cut) in alignment with themechanical axis 202 of the leg.

The illustrated distal femoral condyle block 638 is designed with themounting portion 640 extending across the full width of the femoral pinguide 514 (FIG. 72B) and the paddle 642 extending across the full widthof the distal medial condyle (FIGS. 72A and 73). However, the distalfemoral condyle block 638 may be designed with a narrower mountingportion 640, and optionally a narrower paddle 642, so that the distalfemoral condyle block 638 may be used simultaneously with theWhiteside's angle gage assembly 696 described below. Referring brieflyto FIGS. 75-77, the narrower mounting portion 640 may couple to thedistal medial portion of the femoral riser 504. The paddle 642 wouldstill rest against the distal aspect of the medial femoral condyle.

The distal femoral condyle block 638 may be designed to couple to theangle block assembly 652 described next, for example, to the dovetailchannel 668; or to the Whiteside's angle gage assembly 696, for example,to the distal dove tail rail 706. Advantageously, this allows the distalfemoral condyle block 638 to slide proximally and distally with respectto the femur 100.

Referring to FIGS. 56A and 56B, an angle block assembly 652 includes anangle block 654, a translation bar 656, a translation pin 658, a bolt660, and a dowel pin 662. Referring to FIG. 35, the angle block assembly652 is analogous to the femoral base block assembly 330.

Referring to FIGS. 57A and 57B, the angle block 654 includes a dovetailchannel 668 with a notch 670 at one end (the upper or anterior end, inuse). The angle block 654 also includes an integral clamp ring 672opposite the dovetail channel 668. The clamp ring includes a slit 674that extends through a side of the clamp ring, and a slot 676 thatextends between the clamp ring 672 and the dovetail channel 668 alongpart of the width of the angle block 654. The slit 674 and the slot 676intersect so that the clamp ring 672 has appropriate flexibility forclamping. A hole 678 extends through the clamp ring 672 across the slit674. Another hole 680 extends through the clamp ring opposite the slit674.

The translation bar 656 includes a post 682, a body 684, and a pin 686.These parts may be integrally formed as shown, or separate parts coupledtogether. The post 682 includes an exterior circumferential groove 688.The body may include one or two holes 690; one hole 690 is illustrated.Bilateral flats 692 may extend along opposite sides of the pin 686.

The translation pin 658 is a cylindrical part with a rounded end and anopposite end having a reduced diameter 694 compared to the rest of thepart.

The angle block assembly 652 may be assembled as follows. The hole 690receives the reduced diameter 694 end of the translation pin 658. Thetranslation pin 658 may be permanently fixed in the hole 690. The clampring 672 receives the post 682. The hole 680 and the groove 688 receivethe dowel pin 662 to retain the translation bar 656 to the angle block654 while permitting the translation bar 656 to rotate about the post682 when the clamp ring 672 is loosened. The hole 678 receives the bolt660 which is used to tighten and loosen the clamp ring 672.

The angle block assembly 652 may be coupled to the femoral riser 504.The hole 572 receives the pin 686 and the hole 574 receives the pin 658so that the translation bar 656, with attached translation pin 658, isconstrained to slide straight in and out of the femoral riser 504. Inuse, the pins 686, 658 extend proximally and the dovetail channel 668faces distally.

Referring to FIGS. 58A and 58B, a Whiteside's angle gage assembly 696includes a body 698, a shaft 700, and a cap 702. The body 698 includes aproximal dovetail rail 704 and a distal dovetail rail 706. A tab 708extends from one end of the proximal dovetail rail 704 (the upper oranterior end, in use). A hole 710 extends through the body 698. Thedovetail rails 704, 706 and the hole 710 are all parallel. The shaft 700is a cylindrical part with a rounded end 712 and an opposite end 714terminating in a threaded portion. The rounded end 712 includes anexternal flange 716. Indicia 718 may be provided on the shaft 700, suchas a millimeter or inch scale, or a scale relating to available implantsizes. The cap 702 includes a threaded socket 720 in one end.

The Whiteside's angle gage assembly 696 may be assembled as follows. Theshaft 700 is inserted into the hole 710 so that the threaded end 714protrudes next to the tab 708. The end 714 is threaded into the threadedsocket 720.

The Whiteside's angle gage assembly 696 may be coupled to the angleblock assembly 652 by sliding the proximal dovetail rail 704 into thedovetail channel 668 until the tab 708 is fully seated in the notch 670.With the clamp ring 672 loosened, the shaft 700 may be adjusted to alignparallel with Whiteside's line of an intact distal femur 102. The clampring 672 may be tightened by turning the bolt 660 to lock the angleblock 654 relative to the translation bar 656, thus saving the angle ofthe Whiteside's line for future use. More specifically, the dovetailchannel 668 is locked parallel to the Whiteside's line. The indicia 718may be read at this time, for example the anterior-posterior femoraldimension or femoral implant size.

Referring to FIGS. 59A and 59B, a cut guide mounting block assembly 722includes a mounting block 724, a distal dovetail rail 726, a first screw728, and a second screw 730.

Referring to FIG. 60, the mounting block 724 includes a proximaldovetail rail 732. A tab 734 extends from one end of the proximaldovetail rail 732 (the upper or anterior end, in use). A first plate 736extends parallel to the proximal dovetail rail 732; in use, the firstplate extends in the anterior-posterior and medial-lateral directions. Asecond plate 738 extends perpendicular to the first plate 736; in use,the second plate extends in the proximal-distal and medial-lateraldirections. The proximal dovetail rail 732, first plate 736, and secondplate 738 may be integrally formed as shown, or may be separate partscoupled together. A first hole 740 extends in the proximal-distaldirection through the proximal dovetail rail 732. A second hole 742extends parallel to the first hole 740 through the first plate 736.

The distal dovetail rail 726 includes a first hole 744 and a second hole746. The holes 744, 746 are parallel and extend in the proximal-distaldirection into a proximal surface 748 of the distal dovetail rail 726.

The cut guide mounting block assembly 722 may be assembled as follows.The proximal surface 748 of the distal dovetail rail 726 is placedagainst the distal aspect of the first plate 736. The holes 740, 744 arealigned and the holes 742, 746 are aligned. The first screw 728 isinserted through the hole 740 and threaded into the hole 744. The secondscrew 730 is inserted through the hole 742 and threaded into the hole746.

The cut guide mounting block assembly 722 may be coupled to the angleblock assembly 652 by sliding the proximal dovetail rail 732 into thedovetail channel 668 until the tab 734 is fully seated in the notch 670.

Referring to FIGS. 61A and 61B, a four-in-one cut guide 750 is agenerally rectangular plate with a proximal surface 752, an oppositedistal surface 754, a first slot 756, a second slot 758, a third slot760, and a fourth slot 762. Bilateral slots 758, bilateral slots 760,and bilateral slots 762 are shown. The slots 756, 762 may be the samewidth and may be narrower than the slots 758, 760. There may be justenough room to pass a saw blade through the slot 756 or the slot 762 tomake an anterior femoral resection 214 or a posterior femoral resection220, respectively. The slots 756, 762 may be said to define cuttingpaths of the saw blade acting through the slots. The slots 756, 762 maybe referred to as saw slots or cut guide slots. The slot 760 may benarrower than the slot 758.

The four-in-one cut guide 750 may be coupled to the cut guide mountingblock assembly 722 by inserting the second plate 738 through the slot756 from distal to proximal.

Referring to FIGS. 62A and 62B, the tibial connection block 508 includesa mounting plate 764, a second plate 766, and a distal protrusion 768.In use, the mounting plate 764 extends in the proximal-distal andmedial-lateral directions. The second plate 766 extends perpendicular tothe mounting plate 764 in the anterior-posterior and medial-lateraldirections. The distal protrusion 768 extends distally from the secondplate 766, and is adjacent to a medial or lateral side of the secondplate. The mounting plate 764, second plate 766, and distal protrusion768 may be integrally formed as shown, or may be separate parts coupledtogether. The distal protrusion 768 may form a right angle channel asshown, or may include a socket that opens distally, for example a squaresocket. Bilateral holes 770 extend in the anterior-posterior directionthrough the mounting plate 764. These holes 770 receive the same pegs646 described previously for the distal femoral condyle block 638 (FIGS.55A and 55B). Alternately, the pegs may be integrally formed with themounting plate 764. A hole 772 extends in the proximal-distal directionthrough the second plate 766. This hole 772 may receive and stabilize adistractor jaw tip. The second plate 766 includes a proximal surface774. The tibial connection block 508 may be analogous to a middleportion of the tibial-femoral pin guide 310.

The tibial connection block 508 releasably couples to the femoral riser504. The pegs 646 fit into the mounting holes 584 so that the proximalsurface 774 faces the distal portion 566.

The tibial pin guide 510 includes a bar 776, a proximal protrusion 778,and a distal boss 780. In use, the bar 776 extends in the medial-lateraldirection, the proximal protrusion 778 extends proximally from one endof the bar 776, and the distal boss 780 extends distally from the centerof the bar 776. The bar 776, proximal protrusion 778, and distal boss780 may be integrally formed as shown, or may be separate parts coupledtogether. Bilateral holes 782 extend in the anterior-posterior directionthrough the bar 776. These holes 782 receive bone pins. A slanting hole784 extends through the distal boss 780 from postero-proximal toantero-distal. The distal boss 780 is analogous to the boss 378 of thetibial-femoral pin guide 310 (FIGS. 28A-28B and the hole 784 isanalogous to the hole 382.

The tibial pin guide 510 may be coupled to the tibial connection block508 by inserting the proximal protrusion 778 in the distal protrusion768. Not shown, a fastener may extend through a slot in the distalprotrusion and into a socket, such as a threaded hole, in the proximalprotrusion so that the tibial pin guide 510 is lockably slidable in theproximal-distal direction relative to the tibial connection block 508.Referring to FIGS. 28A and 28B, the coupled tibial pin guide 510 andtibial connection block 508 may be analogous to the tibial-femoral pinguide 310.

The tibial pin guide 510 may be designed to couple to the angle blockassembly 652 instead of the tibial connection block 508. The tibial pinguide 510 may be modified to include a dovetail rail, like the proximaldovetail rail 704 of the Whiteside's angle gage assembly 696 (FIGS. 58Aand 58B), which couples to the dovetail channel 668 of the angle blockassembly 652 (FIGS. 57A and 57B).

The tibial riser 509 includes a proximal end 904 with a notch 906 thatis complementary to the distal boss 780 of the tibial pin guide 510 anda slanting hole 908 that extends into the first end 904 frompostero-proximal to antero-distal. The tibial riser 509 includes adistal end 910 that is divided into two arms 912 separated by a slot914. A transverse hole 916 extends through the arms 912 and across theslot 914.

The tibial riser 509 may be coupled to the tibial pin guide by abuttingthe distal boss 780 in the notch 906 so that the holes 784, 908 arealigned, and inserting a fastener through the holes. Alternately, thetibial riser 509 and the tibial pin guide 510 may be integrally formedas a single part. The tibial pin guide 510 may be coupled to the tibialriser 312 (FIGS. 29A and 29B) (with attached tibial extension rod 313)by inserting distal boss 780 into notch 380 and inserting a fastenerthrough holes 784, 384. Alternately, the tibial riser 312 may bepermanently rigidly coupled to the tibial pin guide 510.

The tibial extension rod 511 may be identical to the femoral extensionrod 506 (FIGS. 54A and 54B), and is shown this way in this application.More specifically, the illustrated tibial extension rod 511 includes theouter extension rod 604, the inner extension rod 606, the spool 608, thesleeve 610, the ring 612, and the retaining ring 614, which areassembled and function as described previously for the femoral extensionrod 506.

The assembled tibial extension rod 511 may be coupled to the tibialriser 509 by inserting the end of the inner extension rod 606 with thehole 624 into the slot 914, aligning the hole 602 with the hole 916, andinserting a fastener through the holes 602, 916 to form a hinge 917(FIGS. 47B and 49B). The tibial extension rod 511 is free to pivot aboutthe hinge 917. In use, the tibial extension rod 511 pivots in ananterior-posterior direction which is generally parallel to the sagittalplane. The tibial extension rod 511 is constrained against pivoting in amedial-lateral direction which is generally parallel to the coronalplane. The end of the inner extension rod 606 with the hole 624 is theproximal end of the tibial extension rod 511, and the end of the outerextension rod 604 with the retaining ring 614 is the distal end of thetibial extension rod 511.

Referring to FIGS. 63A-64B, a femoral support arm assembly 786 includesa post 788, a bar 790, a first clamp body 792, a second clamp body 794,a spring 796, a retaining ring 798, a thumbscrew 800, and a screw 802.The post 788 threads into a socket 804 of the first clamp body 792. Thebar 790 is inserted into a socket 806 of the second clamp body 794 andthe screw 802 is threaded into a hole 808 of the bar to fix the bar 790in the socket 806. The spring 796 is sandwiched between the first andsecond clamp bodies 792, 794. The thumbscrew 800 is inserted through ahole 810 through the second clamp body 794 and a passageway 812 throughthe spring 796, and threaded into a hole 814 through the first clampbody 794. The retaining ring 798 fits around the threaded tip of thethumbscrew 800 to prevent unintentional disassembly of the thumbscrew800, second clamp body 794, spring 796, and first clamp body 794. Whenthe thumbscrew 800 is tightened, the bar 790 is held in a fixedorientation relative to the post 788. When the thumbscrew 800 isloosened, the bar 790 may be rotated relative to the post 788 about thethreaded shaft of the thumbscrew. The post 788 may be clamped to anoperating table. The bar 790 may include bilateral flats 816 that extendthe length of the post 788. While the femoral support arm assembly 786is presented in the context of supporting the target clamp assembly 818discussed next, it also has utility as a tool holder in the immediateoperative site, when outfitted with clamp-on tool holders.

Referring to FIGS. 86A and 86B, a femoral head finder 918 is a T-shapedpart with a body 920 and a stem 922. The body 920 forms the crossbar ofthe T-shape and the stem 922 forms the upright of the T-shape. The body920 includes a deep groove or channel 924 that extends along the lengthof the body 920 so that the body is open along its bottom side.

The femoral head finder 918 may be coupled to the bar 790 of the femoralsupport arm assembly 786; the bar 790 is received in the channel 924.Note that the channel 924 has flat interior sides that are complementaryto the flats 816 of the bar 790 so that the femoral head finder 918 doesnot rotate about the bar 790.

Referring to FIGS. 87A and 87B, a collar 926 is a ring with a radialhole 928 through a side wall of the ring. The hole 928 may be threadedto receive a set screw (not shown). The collar 926 may be coupled to thebar 790; the bar 790 is received in the collar 926. The set screw may betightened in the hole 928 to lock the collar 926 to the bar 790.

Referring to FIGS. 65A-66B, a target clamp assembly 818 includes atarget 820, a retaining ring 822, a first clamp body 824, a second clampbody 826, a lever 828, a link 830, and a pin 832. The example shows twolinks 830 and eight pins 832. The target 820 includes a slot 834 formedbetween a pair of uprights 836. The target may be called a goalpost ortuning fork. A ring, reticle, cross hairs, or the like may substitutefor the goalpost design. The link 830 is preferably compliant orelastic.

A hole 838 of the first clamp body 824 receives a post 840 of the target820; the retaining ring 822 engages a circumferential external groove842 around the tip of the post 836 to prevent unintended disassembly ofthe first clamp body 824 and the target 820. The lever 828 is positionedbetween arms 844 of the first clamp body 824 so that hole 846 alignswith hole 848. A pin 832 is inserted into holes 846, 848 from each sideof the first clamp body 824. Links 830 are positioned in notches 850 ofthe lever 828 so that holes 852 align with holes 854. A pin 832 isinserted into holes 852, 854 from each side of the lever 828. The links830 are positioned in notches 856 of the second clamp body 826 so thatholes 858 align with holes 860. A pin 832 is inserted into holes 858,860 from each side of the second clamp body 826. Tabs 862 of the secondclamp body 826 are positioned in notches 864 of the first clamp body 824so that holes 866 align with holes 868. A pin 832 is inserted into holes866, 868 from each side of the first clamp body 824. Preferably, a widthof the first clamp body 824, in the direction of the holes 846, 866, isequal to the length of the body 920 of the femoral head finder 918.

The target clamp assembly 818 couples to the bar 790 of the femoralsupport arm assembly 786. With the lever 828 lifted so that the firstand second clamp bodies 824, 826 are open, the bar 790 is receivedbetween the first and second clamp bodies. The lever 828 is lowered tourge the first and second clamp bodies 824, 826 against the bar 790. Thelinks 830 are preferably compliant, elastic, or resilient, and mayfunction as extension springs in the target clamp assembly 818.

While the target clamp assembly 818 is shown with a captive target 820,alternative clamp assemblies are contemplated that have other functionalstructures besides the target 820, for example replacing the target witha universal receiver for various tools.

Referring to FIGS. 67A-68B, a foot holder assembly 870 includes a footholder 872, a lower bar 874, a post 876, an upper bar 878, a targetmounting block 880, a target 882, and a thumbscrew 884. Four thumbscrewsare included in the example shown. The post 876 may be received ineither one of the bilateral sockets 886 in the lower bar 874 and fixedin place with a thumbscrew. The foot holder 872, which may be called aboot, rests in a concave portion 888 of the lower bar 874, and may becoupled to the lower bar 874 temporarily or permanently. The lower bar874 may be coupled to the foot holder 872 anywhere along theproximal-distal length of the foot holder. The post 876 is also receivedin a hole 890 in the upper bar 878 and fixed in place with a thumbscrew884. The post 876, sockets 886, and hole 890 are all hexagonal in thisexample, although other non-circular or circular shapes arecontemplated. The target mounting block 880 includes a tab 892 which isreceived in an elongated slot 894 through the upper bar 878. The tab 892includes a hole 896 into which a thumbscrew 884 threads to fix thetarget mounting block 880 in place during use. The target mounting block880 includes another hole 898 which receives a post 900 of the target.The upper bar 878, target mounting block 880, target 882, and associatedthumbscrew 884 may be replaced by the bar 790 (FIGS. 63A-64B) and targetclamp assembly 818. More than one lower bar 874 may be coupled to thefoot holder 872 simultaneously, in which case each lower bar 874 mayhave an associated post 876, upper bar 878, target mounting block 880,target 882, and thumbscrews 884; or bar 790 and target clamp assembly818.

Methods of using the instrument system 500 will now be described withreference to FIGS. 69-85.

Referring to FIG. 69, the femur 100, tibia 104, and fibula 122 are shownwith the knee in full extension to represent a patient lying on anoperating table during preparations for surgery. The femoral support armassembly 786 is shown in position relative to the patient's leg, and maybe clamped to the operating table in this position before being draped.The bar 790 extends horizontally over the patient's pelvis.

Referring to FIG. 70, the femoral support arm assembly 786 may bepositioned proximal (or distal) to the femoral head 118 so that thefemoral head is exposed for radiographic or fluoroscopic imaging.Alternatively, the femoral support arm assembly 786 may be positioneddirectly over the center 120 of the femoral head 118, particularly ifthe bar 790 is radiolucent. The femoral head finder 918 has been coupledto the bar 790 and positioned along the bar so that the stem 922 extendsover the center 120 of the femoral head 118. Radiographs, fluoroscopy, aC-arm, or other imaging may be used to verify that the stem 922 extendsover the center 120 of the femoral head 118. The collar 926 has alsobeen coupled to the bar 790 and positioned abutting the femoral headfinder 918. After the stem 922 is positioned over the center 120 of thefemoral head 118, the collar 926 may be locked to the bar 790. Thefemoral head finder 918 may then be removed from the bar 790. Thesesteps shown in FIG. 70 are preferably performed before the patient issterile draped and before the tourniquet is tightened. FIG. 70 alsoshows that a provisional tibial resection 210 has been made. Theprovisional tibial resection 210 may be made with the knee in fullextension or in flexion. This step shown in FIG. 70 is performed afterthe patient is sterile draped and after the tourniquet is tightened.

Referring to FIG. 71, the target clamp assembly 818 has been coupled tothe bar 790 of the femoral support arm assembly 786. Advantageously,this can occur after the femoral support arm assembly 786 has beencovered with a drape 902, which is depicted as being sheer so that thefemoral support arm assembly can be seen. The compliant, elastic, orresilient links 830 adjust to accommodate the thickness of the drape902. The target 820 may be positioned proximal (or distal) to thefemoral head 118, or directly over the center 120 of the femoral head,particularly if the target 820 is radiolucent. In this application, atarget may be “over the center of the femoral head” even if the targetis actually superior or inferior to the femoral head, so long as thefemoral extension rod passes over the center of the femoral head whenthe femoral extension rod is aimed at the target. The target clampassembly 818 has been coupled to the bar 790 directly adjacent to thecollar 926. The bar 790 and the collar 926 are non-sterile and beneaththe drape 902, while the target clamp assembly 818 is sterile and abovethe drape 902. This detail is noteworthy because the center 120 of thefemoral head 118 may be objectively and precisely found in thenon-sterile pre-operative phase, and transferred to the sterileoperative phase by feeling the collar 926 through the sterile drape andpositioning the target clamp assembly 818 next to the collar 926.

Referring to FIGS. 72A and 72B, the base 502 and femoral riser 504 havebeen coupled together for a left knee. The distal femoral condyle block638 and the femoral extension rod 506 have been coupled to the femoralriser 504. The base 502 is being positioned against the anterior distalfemur 102 and centered in the medial-lateral width of the distal femur102, the paddle 642 is against the medial distal femoral condyle, andthe femoral extension rod 506 is being aligned with the mechanical axis202 of the leg (at least where it crosses the femur 100). The spool 608is in the target 820.

Optionally, the angle block assembly 652 and the Whiteside's angle gageassembly 696 may be used during this step to assist in centering thefemoral riser 504 and base 502 in the medial-lateral width of the distalfemur 102, optionally using a narrow distal femoral condyle block 638,or a distal femoral condyle block that couples to the Whiteside's anglegage assembly 696. The angle block assembly 652 may be coupled to thefemoral riser 504 and the Whiteside's angle gage assembly 696 may becoupled to the angle block assembly 652, with the shaft 700 of theWhiteside's angle gage assembly 696 extending within the intercondylarnotch (trochlear notch), similar to the arrangement shown in FIG. 77,but without bone pins through the femoral pin guide 514. The base 502may then be moved medial or lateral to center the shaft 700 in theintercondylar notch.

Optionally, a bone pin or screw may be driven into the distal femur 102through a hole (not shown) that is centered between the mounting holes584 of the femoral pin guide 514. The screw holds the femoral riser 504and base 502 centered in the medial-lateral width of the distal femur102 and serves as a pivot post about which the femoral riser 504, base502, and the femoral extension rod 506 can rotate in the medial-lateraldirection so that the femoral extension rod may be positioned over thecenter 120 of the femoral head 118.

Referring to FIG. 73, the femoral riser 504 has been pinned to thedistal femur, along with the attached base 502 and femoral extension rod506. The base 502 is under the suprapatellar fat pad 116 against theanterior distal femoral cortex and centered in the medial-lateral widthof the distal femur 102, the paddle 642 is against the medial distalfemoral condyle, and the femoral extension rod passes over the center120 of the femoral head 118 and between the uprights 836 of the target820. The bone pins extend into the distal femur in the metaphyseal, ormetaphyseal equivalent, region as opposed to the diaphyseal orepiphyseal regions.

Depending upon bone quality and the configuration of any frictionalelements protruding from the bone contacting surface 518 of the base502, the bone contacting surface 518 may actually be spaced apartslightly from the anterior distal femoral cortex, rather than directlyagainst the cortex. For example, in hard bone, the spikes 538 alone maybear against the cortex. In this situation, the three spikes 538 may besaid to define a theoretical bone contacting plane. The theoretical bonecontacting plane functions the same as the actual bone contactingsurface 518, and is interchangeable with the actual bone contactingsurface 518 in this specification.

Referring to FIG. 74, the distal femoral condyle block 638 has beenremoved.

Referring to FIG. 75, the angle block assembly 652 has been coupled tothe femoral riser 504. The clamp ring 672 has been loosened. The knee isshown in flexion in FIGS. 71-75, but may instead be in full extensionduring these steps.

Referring to FIG. 76, the Whiteside's angle gage assembly 696 has beencoupled to the angle block assembly 652.

Referring to FIG. 77, the shaft 700 has been aligned with Whiteside'sline and the clamp ring 672 has been tightened to save the orientationof the Whiteside's line in the angle block assembly 652. The knee isshown in flexion in FIGS. 76-77; this is preferable because it improvesvisibility of Whiteside's line.

Referring to FIG. 78, the Whiteside's angle gage assembly 696 and theangle block assembly 652 have been removed from the femoral riser 504and the distal femoral condyle block 638 has been replaced. A distalfemoral resection 206 has been made, guided by the distal femoralcondyle block 638. Preferably, the distal femoral resection 206 is madeperpendicular to the mechanical axis 202 of the leg.

Referring to FIG. 79, the distal femoral condyle block 638 has beenremoved again. The knee is shown in flexion in FIGS. 78-79, but mayinstead be in full extension during these steps.

Referring to FIGS. 80A-B, the knee is in full extension, the foot hasbeen secured within the foot holder assembly 870, the tibial connectionblock 508 has been coupled to the femoral riser 504, and the tibial pinguide 510 has been coupled to the tibial connection block 508 inpreparation for the step of aligning the tibia to the mechanical axis202 of the leg. In FIG. 80A, the tibial pin guide 510 is coupled to thetibial riser 509, which is coupled to the telescoping tibial extensionrod 511. In FIG. 80B, the tibial pin guide 510 is shown in an alternatearrangement coupled to the tibial riser 312, which is coupled to thetelescoping tibial extension rod 313. The proximal surface 774 of thetibial connection block 508 may be against the distal femoral resection206. Other femoral resections 214, 216, 218, 220 may have been performedprior to this step. The foot holder assembly 870 is readily adaptable tohold the tibial target 882 over the anterior tibial crest or the tibialtuberosity, or any other location along the length of the tibia, ankle,or foot. Multiple tibial targets may be used, for example, one tibialtarget over the distal tibia/ankle and another tibial target over thetibial tuberosity.

As an alternative to a tibial target that is mounted to the foot holderassembly 870, a tibial target may be directly coupled to the tibia. Forexample, two bone pins may be placed in the proximal anterior tibia, oneon either side of the tibial tuberosity, to serve as a proximal tibialtarget. The bone pins may be placed using a hand-held pin guide (notshown). The bone pins may be spaced apart so that the tibial riser 312or 509 fits between the bone pins, is closely constrained by the bonepins to prevent medial-lateral translation, and is free to pivot in themedial-lateral direction so that the tibial extension rod 313 or 511 maybe aimed at the distal tibial target.

Referring to FIGS. 80B and 80C, one can appreciate that the femoralextension rod 506 and the tibial extension rod 313 or 511 are collinearin an anterior view.

Referring to FIG. 80C, the tibial pin guide 510 is shown coupled to thetibial riser 312, which is coupled to the telescoping tibial extensionrod 313. Alternately, the tibial pin guide 510 may be coupled to thetibial riser 509, which is coupled to the telescoping tibial extensionrod 511. The tibia 104 has been aligned to the mechanical axis 202 ofthe leg so that the entire leg is aligned: femoral head center 120,distal femur 102, proximal tibia 106, and, in this example, the ankle.Preferably, the knee joint is distracted to the extent permitted by theexisting ligamentous structures of the knee while the tibia 104 isaligned to the mechanical axis 202. Now parallel bone pins may beinserted through the holes 782 of the tibial pin guide 510 into thetibia 104 in preparation for further surgical steps involving the tibia104. The tibial pin guide 510 may be removed from the tibia, leaving theparallel bone pins behind. A subsequent instrument may be coupled to thetibia by sliding the instrument over the parallel bone pins. Forexample, the tibial cut guide 328 of FIGS. 34A-34B may be placed overthe tibial bone pins, and a saw used through the tibial cut guide tomake a proximal tibial resection 210.

Referring to FIG. 81, the surgical procedure has turned to the femur100. The angle block assembly 652 has been reattached to the femoralriser 504, and the clamp ring 672 remains tight, maintaining thealignment of Whiteside's line (FIG. 77) for the subsequent steps.

Referring to FIG. 82, the cut guide mounting block assembly 722 has beencoupled to the angle block assembly 652.

Referring to FIG. 83, the four-in-one cut guide 750 has been coupled tothe cut guide mounting block assembly 722.

Referring to FIG. 84, the four-in-one cut guide 750 has been aligned inthe medial-lateral direction and positioned against the distal femoralresection 206. At this point, bone pins may be driven through medial andlateral holes (not shown) in the four-in-one cut guide 750 to secure theguide 750 to the distal femur.

Alternately, a drill bit or bone pin may be driven through a slot of thefour-in-one cut guide 750 so that the drill extends in a proximal-distaldirection, parallel to the bone contacting surface 518 of the base 502,at the level of the spikes 538. The drill bit or bone pin acts as ahanger for the four-in-one cut guide 750 while permitting rotational andside-to-side adjustment of the four-in-one cut guide. Rotationalalignment may be provided by a block with an inclined plane, wherein theblock is seated on the proximal tibial resection 210, wherein thefour-in-one cut guide 750 rests on the inclined plane, wherein the planeis inclined in the medial-lateral direction and is higher under thelateral condyle. The plane may be 3 mm higher under the lateral condyle.

Referring to FIG. 85, the cut guide mounting block assembly 722, theangle block assembly 652, the femoral riser 504, and the base 502 havebeen removed from the femur 100, leaving only the four-in-one cut guide750 secured to the femur. However, as explained above, preferably thefemoral riser 504 and base 502 remain coupled to the femur 100 in thisstep. An anterior femoral resection 214 has been made through the slot756. The anterior femoral resection 214 and the bone contacting surface518 of the base 502 lie in a common plane.

After making the femoral resections 206, 214, 216, 218, and/or 220, thesurgical procedure may turn to the tibia 104. The next step may be toalign the tibia to the mechanical axis 202 of the leg as described forFIGS. 80A-80C. Alternately, the next steps may include coupling thetibial cut guide 328 (with the desired slope) to the proximal tibialbone pins previously placed using the tibial pin guide 510 and creatinga final proximal tibial resection 210 through the tibial cut guide 328.

Referring to FIG. 88, after the femur 100, tibia 104, and optionallypatella 112 are prepared, knee arthroplasty implants may be secured tothe prepared bone surfaces. FIG. 88 is an isometric view of a knee jointwith a femoral component 130, a tibial component 132, an articularinsert 134, and a patellar component 136. The patellar component 136 isshown exploded from the patella for clarity, since the patellarcomponent would otherwise be hidden by the patella in this view.Unicondylar or unicompartmental implants may be implanted instead of thetotal knee components shown.

FIGS. 89-120 illustrate yet another instrument system 1500.

FIG. 89 shows the step of securing a foot (not shown, the lower leg isrepresented by the tibia 104 and fibula 122) in a portion of a footholder assembly 1870. The foot holder assembly 1870 includes a footreceiver 1872, a lower bar 1874, a bridge 1878, a target mounting block1880, a dovetail lock 1881, a target 1882, and a thumbscrew 1884. Thebridge 1878, target mounting block 1880, dovetail lock 1881, target1882, and thumbscrew 1884 are shown in FIGS. 94-95C.

FIG. 90 shows the step of securing a femoral support arm assembly 1786to an operating table (not shown) so that a portion of the femoralsupport arm assembly extends over the hip area. This step may be similarto or identical to the step of FIG. 69. The femoral support arm assembly1786 includes a post 1788, a bar 1790, a first clamp body 1792, a secondclamp body 1794, a spring 1796, a retaining ring 1798, a thumbscrew1800, and a screw 1802. The femoral support arm assembly 1786 may besimilar to or identical to the femoral support arm assembly 786 or 2786.

FIG. 91 shows the step of positioning a femoral head finder 1918 toextend over the center 120 of the head 118 of the femur 100. Thisalignment may be verified using imaging, for example fluoroscopy. 70.The femoral head finder 1918 may be similar to or identical to thefemoral head finder 918 or 2918.

FIG. 92 shows the step of securing a collar 1926 to the bar 1790 besidethe femoral head finder 1918. The steps of FIGS. 91 and 92 may besimilar to or identical to the step of FIG. 70. The collar 1926 may besimilar to or identical to the collar 926 or 2926. Preferably, the stepsof FIGS. 89-92 may occur before sterile draping of the patient.

FIG. 93 shows the step of removing the femoral head finder 1918 andsecuring a target clamp assembly 1818 to the bar 1790 beside the collar1926. This step may be similar to or identical to the step of FIG. 71.Preferably, this step may occur after the femoral support arm assembly1786 has been covered with a sterile drape, such as drape 902 of FIG.71. Thus the collar 1926 and the femoral support arm assembly 1786 maybe nonsterile under the drape, and the target clamp assembly 1818 may besterile above the drape. The target clamp assembly 1818 includes atarget 1820, a retaining ring 1822, a first clamp body 1824, a secondclamp body 1826, a lever 1828, a link 1830, and a pin 1832. The exampleshows two links 1830 and eight pins 1832. The target clamp assembly 1818may be similar to or identical to the target clamp assembly 818 or 2818.

FIG. 94 shows the step of assembling the bridge 1878, target mountingblock 1880, dovetail lock 1881, target 1882, and thumbscrew 1884 to thelower bar 1874 and the foot receiver 1872 to form a complete foot holderassembly 1870. FIGS. 95A-95C show the foot holder assembly 1870.

The lower bar 1874 includes bilateral sockets 1000, 1002 on either sideof a concave portion 1004. The lower bar 1874 may be similar to oridentical to the lower bar 874 or 2874. The bridge 1878 is ahorseshoe-shaped or U-shaped part with a central bridge 1006 and twolegs 1008, 1010, each leg extending from an end of the bridge 1006 andterminating in a free end. The free ends have tabs 1012, 1014,respectively. Each tab bifurcates at its tip to form a resilient snapfeature. The bridge 1006 includes a through slot 1016 that extendsbetween back to back pockets 1018, 1020. The target 1882 is a generallyspoon-shaped or ladle-shaped part with an elongated stem 1022 thatterminates in a bowl 1024 at one end. The stem 1022 includes an undercutrail 1026 that extends along the length of the stem. The target mountingblock 1880 has a generally rectangular or square body with a rectangularor square through hole 1028. An undercut channel 1030 extends across oneside of the target mounting block 1880 and across the hole 1028. Theopposite side of the target mounting block 1880 includes bilateralshelves or ledges 1032, 1034 that extend transverse to, or perpendicularto, the undercut channel 1030. The dovetail lock 1881 is an elongatedpart that includes a generally rectangular or square body 1036 with athreaded shaft 1038 extending from one side of the body. Bilateralshelves or ledges 1038, 1040 extend across this side of the body onopposite sides of the shaft 1038. Opposite the shaft 1038, an undercutchannel 1044 extends across the body 1036 transverse to, orperpendicular to, the bilateral ledges 1038, 1040. The thumbscrew 1884includes a mushroom-shaped body 1046 with a threaded socket 1048opposite the enlarged mushroom “cap.” The foot receiver 1872 may besimilar to or identical to the foot holder 872 or the foot receiver2872.

The tab 1012 is received in the socket 1000 and the tab 1014 is receivedin the socket 1002. The tabs 1012, 1014 may snap into and out ofengagement with the sockets 1000, 1002. The target mounting block 1880is at least partially received in the pocket 1018 or 1020 so that theledges 1032, 1034 rest atop the pocket walls. The target mounting block1880 is shown in the pocket 1018. The body 1036 of the dovetail lock1881 is at least partially received in the hole 1028 in the targetmounting block 1880 so that the undercut channels 1030, 1044 face thesame direction and are aligned, and so that the shaft 1038 extendsthrough the slot 1016 of the bridge 1878 and threads into the socket1048 of the thumbscrew 1884. The thumbscrew 1884 is partially receivedin the pocket 1018 or 1020, whichever one is not occupied by the targetmounting block 1880. The thumbscrew 1884 is shown in the pocket 1020.The undercut rail 1026 of the target 1882 is received in the undercutchannels 1030, 1044. Tightening the thumbscrew 1884 locks the undercutrail 1026 in position relative to the bridge 1878. Loosening thethumbscrew 1884 permits the target 1882 to be moved relative to thebridge 1878 in the anterior to posterior direction and in the medial tolateral direction.

FIGS. 96A and 96B show the step of coupling a femoral pin guide assembly1501 to the anterior distal femur. This step may be similar to oridentical to the step of FIG. 72. This step may include coupling thefemoral pin guide assembly 1501 to the target 1820 of the target clampassembly 1818 via a femoral extension rod assembly 1506 (FIG. 107). Thisstep may include aligning the femoral pin guide assembly 1501 and/or thefemoral extension rod assembly 1506 with the mechanical axis 202 of theleg as it extends through the femur 100. FIGS. 97A-97C show the femoralpin guide assembly 1501, which includes a base 1502, a handle 1516, apin guide 1521, a screw 1513, and a pin sleeve 1515. The example showstwo screws 1513. Aligning the femoral pin guide assembly 1501 and/or thefemoral extension rod assembly 1506 with the mechanical axis 202 of theleg may include centering the base 1502 in the medial-lateral width ofthe distal femur and at the same time aligning the femoral extension rodassembly 1506 to pass over the center 120 of the femoral head 118. Thisstep may include positioning a distal edge of the bone contactingsurface 1518 at the place on the distal anterior femur where theanterior femoral resection 214 is planned to exit the femur.

The base 1502 is an elongated plate with a bone contacting surface 1518and an opposite top surface 1520. The base 1502 has a distal portion1522 and a proximal portion 1524 which tapers to a proximal tip which isnarrower than the distal portion. A longitudinal axis 1503 extends alongthe length of the base 1502 between the distal and proximal portions1522, 1524; only a portion of the axis 1503 is shown for clarity. Thebase 1502 includes a hole 1526 through the distal portion 1522. A pocket1528 is recessed into the bone contacting surface 1518 around the hole1526. The pocket 1528 may be described as a counterbore around the hole1526. The base 302 includes two through holes 1530, 1532 between thedistal and proximal portions 1522, 1524. Each hole 1530, 1532, 1534includes a shelf 1536 on at least one side wall. The shelves 1536 areillustrated as counterbores around the holes 1530, 1532, 1534 but may beunilaterally positioned instead. The base 1502 may include one or morefrictional elements, such as spikes 1538 protruding from the bonecontacting surface 1518. The spikes 1538 in this example are separateset screws with sharp leading tips inserted into corresponding holes1539 in the base 1502.

The handle 1516 includes a base portion 1561 with a bone facing surface1562 and an opposite top side 1564. The base portion 1561 has a distalportion 1566 and a proximal portion 1568. The base portion 1561 has aseries of holes 1571, 1573, 1575, 1577 arranged from distal to proximal.An optional tab 1579 may extend from the top side between holes 1571,1573. A stalk 1570 protrudes from the top side 1564 between the distaland proximal portions 1566, 1568. The stalk 1570 terminates in aproximal free end 1581 with a slot 1583 and through hole 1585.

The pin guide 1521 has a generally arcuate body 1523 that extendsbetween a distal portion 1525 and a proximal portion 1527. The distalportion 1525 includes a longitudinal hole 1529 with a longitudinal slot1531. The hole 1529 and slot 1531 extend in the distal-proximaldirection. The proximal portion 1527 includes a pocket 1533 and holes1535, 1537 which intersect the pocket. The pin sleeve 1515 includes acylindrical shaft 1541 with an enlarged head 1543 at one end and alongitudinal through hole 1545.

The shaft 1541 of the pin sleeve 1515 is received in the hole 1529 ofthe pin guide 1521 so that the head 1543 is distal. The distal portion1566 of the handle 1516 is received in the pocket 1533 of the pin guide1521. One of the screws 1513 extends through the holes 1535, 1571 andthe other screw 1513 extends through the holes 1537, 1573 to secure thepin guide 1521 to the handle 1516. The spikes 1538 are received in theholes 1539; the spikes may optionally be integrally formed with the base1502. A fastener (not shown) extends through the holes 1526, 1575 and asecond fastener extends through the holes 1530, 1577 (for a left knee)or the holes 1532, 1577 (for a right knee) to secure the base 1502 tothe handle. When the pin sleeve 1515, pin guide 1521, handle 1516, andbase 1502 are coupled together as described, the hole 1545 may bealigned with the bone contacting surface 1518, or a theoretical bonecontacting plane defined by the spikes 1538 where the spikes contact thedistal anterior femur. Preferably, the hole 1545 may be parallel to thebone contacting surface 1518, parallel to the upcoming anterior femoralresection 214, or perpendicular to the upcoming distal femoral resection206. The inner rod 1606 of the femoral extension rod assembly 1506 isreceived in the slot 1583 and the pin 1601 extends through hole 1585 andthe inner rod to form a hinge about which the femoral extension rodassembly pivots in use.

FIG. 98 shows the step of placing a femoral pin 1505 into the distalfemur through the pin sleeve 1515 of the femoral pin guide assembly1501. The femoral pin 1505 is received in the hole 1545. Preferably,this step occurs while the bone contacting surface 1518 and/or thespikes 1538 of the base 1502 contact the distal anterior femur, andwhile the femoral pin guide assembly 1501 and/or the femoral extensionrod assembly 1506 are aligned with the mechanical axis 202 of the leg.Preferably, the femoral pin 1505 is placed in strong, dense subtrochlearbone anterior to the femoral intramedullary canal and posterior to theintended location of the upcoming anterior femoral resection 214.

FIG. 99 shows the step of removing the pin sleeve 1515 after the femoralpin 1505 has been placed into the distal femur. The pin sleeve 1515slides distally out of the hole 1529 and distally along the femoral pin1505. This exposes the slot 1531.

FIG. 100 shows the step of removing the femoral pin guide assembly 1501after the femoral pin 1505 has been placed into the distal femur. Thefemoral pin guide assembly 1501 may be lifted anteriorly so that thefemoral pin 1505 exits through the slot 1531. This step may includeremoving the spool 1608 anteriorly from the target 1820. The femoral pin1505 encodes information about 1) the proper varus/valgus orientation ofthe distal femoral resection 206, 2) the flexion/extension orientationof the anterior femoral resection 214 and the posterior femoralresection 220, and 3) the middle of the trochlear groove (Whiteside'sline). The femoral pin 1505 enables rotational adjustment of cut guidesabout the pin 1505, which ensures proper tracking of the patella. Morespecifically, femoral cut guides may be adjusted for varus-valgusrotation about the pin 1505.

FIG. 101 shows the step of placing a tibial centering pin 1507 in thetibial tuberosity to serve as a proximal tibial target. The tibialcentering pin 1507 may be placed freehand or with a guide (not shown).The tibial centering pin 1507 may be centered in the medial-lateralwidth of the proximal tibia 106 and/or centered in the medial-lateralwidth of the tibial tuberosity.

FIGS. 102A and 102B show the step of coupling a three in one cut guideassembly 1321 to the femur 100, the tibia 104, and the foot holderassembly 1870. This step may include sliding a hole of the three in onecut guide assembly 1321 over the femoral pin 1505. This step may includesliding a slot of the three in one cut guide assembly 1321 over thetibial pin 1507. The three in one cut guide assembly 1321 may pivotaround the femoral pin 1505 to a rotational position in which the slotaccepts the tibial pin 1507. This step may include coupling the three inone cut guide assembly 1321 to a tibial extension rod assembly 1511, andcoupling the tibial extension rod assembly to a target 1882 of the footholder assembly 1870. This step may include aligning the three in onecut guide assembly 1321 and/or the tibial extension rod assembly 1511with the mechanical axis of the leg as it extends through the tibia 104.The three in one cut guide assembly 1321 shown in FIGS. 103A-103Cincludes an anterior femoral cut guide 1326, a posterior femoral andtibial cut guide 1328, a tibial rail 1323, and a button assembly 1327.The three in one cut guide assembly 1321 is coupled to a tibialextension rod assembly 1511, which is coupled to the foot holderassembly 1870. FIG. 102B shows that it is preferable for the tibia 104to be positioned so that a tibial shaft axis 201 forms a ninety degreeangle 1315 with the femoral shaft axis 200 of the femur 100. Theanterior femoral cut guide 1326 and the posterior femoral and tibial cutguide 1328 are pinned to the distal femur and proximal tibia,respectively, with femoral pin 1505 and tibial pin 1507. The exampleshows two tibial rails 1323 and two button assemblies 1327. The buttonassembly 1327 includes a button, a spring, and a dowel pin. The tibialextension rod assembly 1511 (FIG. 107) includes an outer rod 1605, aninner rod 1607, a sleeve 1611, a ring 1613, a pin 1601, and a ball 1617.The tibial extension rod assembly 1511 may be similar to or identical tothe tibial extension rod 313, 511, 2511 or the femoral extension rod306, 506, 1506, 2506. Aligning the three in one cut guide assembly 1321and/or the tibial extension rod assembly 1511 with the mechanical axisof the leg may include centering the posterior femoral and tibial cutguide 1328 over the tibial pin 1507 and at the same time aligning thetibial extension rod assembly 1511 to pass over the medial-lateralcenter of the ankle, the second toe, or anterior tibial spine.

The anterior femoral cut guide 1326 has a distal side 1050, an oppositeproximal side 1052, and an anterior side 1054. A saw slot 1056 extendsthrough the anterior femoral cut guide 1326 in a distal to proximaldirection. A boss 1058 extends from a middle portion of the distal side1050. A through hole 1060 extends through the boss 1058. The throughhole 1060 receives the femoral pin 1505, thereby positioning the sawslot 1056 so that the anterior femoral resection 214 will exit the femurat the planned location. Bilateral through holes 1062, 1064 are locatedon either side of the boss 1058. The holes 1062, 1064 may includecounterbores 1066, 1068 as shown in the distal side 1050. The holes1062, 1064 may converge as they extend from distal to proximal.Bilateral rectangular or square through holes 1070, 1072 are located oneither side of the boss 1058; the holes 1070, 1072 are shown outboard ofthe holes 1062, 1064, but could be inboard instead. The holes 1070, 1072extend through the anterior femoral cut guide 1326 in an anterior toposterior direction passing through the anterior side 1054.

The posterior femoral and tibial cut guide 1328 has a distal side 1074,an opposite proximal side 1076, and an anterior side 1078. Saw slots1080, 1082 extend through the posterior femoral and tibial cut guide1328 in a distal to proximal direction. The saw slots 1080, 1082 may beparallel or there may be an acute angle between them. An arm 1084extends distally and posteriorly from a middle portion of the distalside 1074. The free end 1085 of the arm 1084 includes a lengthwise slot1086 and a hole 1088 that extends through the arm and across the slot.Bilateral through holes 1090, 1092 are located on either side of the arm1084. The holes 1090, 1092 may include counterbores 1094, 1096 as shownin the distal side 1074. The holes 1062, 1064 may converge as theyextend from distal to proximal. Bilateral rectangular or square bosses1100, 1102 extend from the distal side 1074 on either side of the arm1084. The bosses 1100, 1102 are shown outboard of the holes 1090, 1092,but could be inboard instead. Rectangular or square pockets 1104, 1106are recessed into the distal aspect of the bosses 1100, 1102. Circularholes 1108, 1110 are recessed into the proximal ends of the pockets1104, 1106. Rectangular or square through holes 1112, 1114 extendthrough the bosses 1100, 1102 in a distal to proximal direction. Ananterior facing shelf 1116 is formed between anterior and posteriorportions of the posterior femoral and tibial cut guide 1328. Bilateralrectangular or square through holes 1118, 1120 are located on eitherside of the boss arm; the holes 1118, 1120 are shown outboard of theholes 1090, 1092, but could be inboard instead. The holes 1118, 1120extend through the posterior femoral and tibial cut guide 1328 in ananterior to posterior direction passing through the anterior side 1078.Posterior facing shelves 1122, 1124 are formed in the proximal side ofthe posterior femoral and tibial cut guide 1328. The shelf 1122 rests onthe proximal aspect of the tibia when the three in one cut guide 1321 isadjusted to an implant size that matches the patient's anatomy.

The tibial rail 1323 is a generally rectangular elongated part with ananterior end 1126, a posterior end 1128, and a proximal side 1130. Aseries of detents 1132, in this example grooves, extends along a middleportion of the proximal side 1130. Indicia 1134 may be present on thetibial rail 1323.

The button assembly 1327 includes a button body 1136, a spring 1138, anda pin 1140. The button body 1136 includes a generally rectangular shaft1142 with an enlarged head 1144 at one end. A generally rectangularthrough hole 1146 extends transversely through the shaft 1142. A throughhole 1148 extends transversely through the shaft 1142 and across thehole 1146.

The anterior ends 1126 of the tibial rails 1323 are received in theholes 1070, 1072 of the anterior femoral cut guide 1326 so that theposterior ends 1128 project posteriorly and the proximal sides 1052,1130 face the same direction. The anterior ends 1126 may be fixed in theholes 1070, 1072. A spring 1138 is received in each hole 1146 of thebutton bodies 1136. The button bodies 1136 are received in the posteriorfemoral and tibial cut guide 1328 so that the shafts 1142 are in theholes 1112, 1114, the springs 1138 are in the holes 1108, 1110, theheads 1144 are in the pockets 1104, 1106, and the holes 1148 are exposedproximally to receive the pins 1140. The posterior ends 1128 of thetibial rails 1323, with attached anterior femoral cut guide 1326, arereceived in the anterior ends of the holes 1118, 1120 of the posteriorfemoral and tibial cut guide 1328 and advanced through the holes 1146 ofthe button bodies 1136 so that the springs 1138 are distal to the tibialrails 1323 and the pins 1140 engage the detents 1132. The inner rod 1607of the tibial extension rod assembly 1511 is received in the slot 1086and the pin 1601 extends through hole 1088 and the inner rod to form ahinge about which the tibial extension rod assembly pivots in use.

FIG. 104 shows the step of further securing the three in one cut guideassembly 1321 to the femur 100 and the tibia 104 by driving bone pins1329 through the anterior femoral cut guide 1326 and the posteriorfemoral and tibial cut guide 1328. Preferably, this step occurs whilethe three in one cut guide assembly 1321 and/or the tibial extension rodassembly 1511 are aligned with the mechanical axis 202 of the leg.

FIG. 105 shows the step of making an anterior femoral resection 214, aposterior femoral resection 220, and a proximal tibial resection 210.The anterior femoral resection 214 is made through the saw slot 1056 inthe anterior femoral cut guide 1326, which is carried on the femoral pin1505, which was positioned in the distal femur while directlyreferencing the distal anterior femoral cortex, notably the desired exitpoint for the anterior femoral resection 214. The posterior femoralresection 220 is made through the femoral saw slot 1080 in the posteriorfemoral and tibial cut guide 1328. The proximal tibial resection 210 ismade through the tibial saw slot 1082 in the posterior femoral andtibial cut guide 1328. Note that the proximal tibial resection 210 ismade while the soft tissues surrounding the knee joint are intact andloaded by the natural anatomy. Thus the conventional step of balancingsoft tissues may be greatly reduced or eliminated altogether.

FIG. 106 shows the step of removing the three in one cut guide assembly1321 after making the anterior femoral resection 214, the posteriorfemoral resection 220, and the proximal tibial resection 210.

FIG. 107 shows the step of coupling a distal femoral cut guide assembly1519 to the femur 100. This step may include coupling the distal femoralcut guide assembly 1519 to the anterior distal femur and the target 1820of the target clamp assembly 1818 via the femoral extension rod assembly1506. This step may include aligning the distal femoral cut guideassembly 1519 and/or the femoral extension rod assembly 1506 with themechanical axis 202 of the leg as it extends through the femur 100. Thedistal femoral cut guide assembly 1519 shown in FIGS. 108A-108C includesa femoral pin block 1514, a femoral riser 1504, a screw 1150, a pin1152, and a distal femoral cut block assembly 1638. The distal femoralcut guide assembly 1519 is coupled to a femoral extension rod assembly1506. The femoral extension rod assembly 1506 includes an outer rod1604, an inner rod 1606, a spool 1608, a sleeve 1610, a ring 1612, aretaining ring 1614, and the pin 1601. The femoral extension rodassembly 1506 may be similar to or identical to the femoral extensionrod 306, 506, 2506 or the tibial extension rod 313, 511, 1511, 2511. Thedistal femoral cut block assembly 1638 shown in FIGS. 108A-108C includesa distal femoral cut block 1637 and two pegs 1646. Aligning the distalfemoral cut guide assembly 1519 and/or the femoral extension rodassembly 1506 with the mechanical axis 202 of the leg may includecentering the femoral pin block 1514 in the medial-lateral width of thedistal femur and at the same time aligning the femoral extension rodassembly 1506 to pass over the center 120 of the femoral head 118. Thisstep may reference four anatomical reference points: the distal marginof the medial femoral condyle, the femoral pin 1505 (which was placed byreferencing the distal anterior femoral cortex and the mechanical axisof the leg), the anterior femoral resection 214, and the mechanical axis202 of the leg (directly).

The femoral pin block 1514 is a roughly triangular plate with a bonefacing surface 1154 and an opposite top surface 1156. The bone facingsurface 1154 is positioned against the anterior femoral resection 214.The femoral pin block 1514 has a distal portion 1566 and a proximalportion 1568. The femoral pin block 1514 is illustrated with severalthrough holes 1162, 1164, 1166 which receive bone pins; two mountingholes 1168 are shown as well. Two proximal holes 1162 are shown, twelvemiddle holes 1164 are shown, and four distal holes 1166 are shown,although any number of holes may be provided. The left and right holes1162 may converge together as they approach the bone facing surface1154. The left group and the right group of holes 1164 may also convergetogether as they approach the bone facing surface 1154. The left groupand the right group of holes 1166 may include individual holes that arespaced apart widely enough in the medial-lateral direction that femoralresections may be cut while the femoral pin block 514 remains secured tothe femur 100. These widely spaced holes 1166 may be located outboard ofthe mounting holes 1168 so that bone pins driven through the widelyspaced holes 1166 penetrate the epicondyles. The femoral pin block 1514may be widened as shown to support the widely spaced holes 1166. Thefemoral pin block 514 includes a blind hole 1170 and a through hole1172. All of the preceding holes 1162, 1164, 1166, 1168, 1170, 1172extend at least through the top surface 1154 of the femoral pin block.The distal portion 1566 includes a transverse undercut channel 1174 witha dimple 1176 in its proximal surface.

The femoral riser 1504 is a generally curved bar with a distal portion1178 and a proximal portion 1180. Two holes 1182, 1184 extend anteriorlyinto the distal portion 1178. The proximal portion 1180 includes alongitudinal slot 1186 and a transverse hole 1188 that extends acrossthe slot 1186.

The distal femoral cut block 1637 includes a proximal mounting portion1190 and a distal paddle 1192. The mounting portion 1190 includes a bar1194 with a peg 1646 extending from each end of the bar. The pegs 1646are parallel, and in this example they are separate pins which arecoupled to holes 1196 in the bar 1194; the pegs 1646 may be integralwith the bar 1194 instead. The bar 1194 includes a saw slot 1198 whichextends in an anterior-posterior direction through the bar 1194. Thepaddle 1192 includes a proximal surface 1200 which is positioned againstthe distal medial condyle. The saw slot 1198 is offset 9 mm from theproximal surface 1200 in the example shown.

The pin 1152 is received in the hole 1170 of the femoral pin block 1514and the hole 1182 of the femoral riser 1504. The screw 1150 extendsthrough the holes 1172, 1184 to secure the femoral pin block 514 and thefemoral riser 1504 together. The pegs 1646 are received in the holes1196 of the distal femoral cut block 1637, and may be press fit orotherwise fixed in place. The pegs are also received in the holes 1168of the femoral pin block 514 to couple the distal femoral cut blockassembly 1638 to the femoral pin block.

FIG. 109 shows the step of further securing the distal femoral cut guideassembly 1519 to the distal femur with bone pins 1329. Preferably, thisstep occurs while the bone facing surface 1154 of the femoral pin block1514 contacts the anterior femoral resection 214, and while the femoralpin guide assembly 1501 and/or the femoral extension rod assembly 1506are aligned with the mechanical axis 202 of the leg. This improves theaccuracy of the distal femoral resection 206.

FIG. 110 shows the step of removing the femoral pin 1505 and making adistal femoral resection 206. The distal femoral resection 206 is madethrough the saw slot 1198 in the distal femoral cut block 1637.

FIGS. 111A and 111B show the step of removing the distal femoral cutblock assembly 1638 and illustrate the adjustability provided by thedistal femoral cut block 1637, an optional insert 1202, and the femoralpin block 1514. The optional insert 1202 may be included in the distalfemoral cut guide assembly 1519 to provide adjustability to the distalfemoral cut. A cut made through the saw slot 1198 of the distal femoralcut block 1637 is in the standard or zero position. If the distalfemoral cut block assembly 1638 is removed, a cut made against thedistal surface 1208 of the insert 1202 is 2 mm proximal to the standardposition. If the insert 1202 is removed, a cut made against the distalsurface 1566 of the femoral pin block 1514 is 4 mm proximal to thestandard position. The insert 1202 is an elongated bar with alongitudinal proximal undercut rail 1204 and a retention tab 1206 on therail.

FIG. 112 shows the step of coupling a chamfer cut guide 1751 to thefemoral pin block 1514 in place of the distal femoral cut block assembly1638. FIGS. 112-113 show views of the chamfer cut guide 1751. Thechamfer cut guide 1751 includes a generally rectangular body 1210 with adistal surface 1212, an opposite proximal surface 1214, and an anteriorsurface 1216. The chamfer cut guide 1751 has two saw slots 1218, 1220which intersect at the distal surface 1212 and diverge anteriorly andposteriorly as they extend toward the proximal surface 1214. Bilateraltabs 1222, 1242 extend from the chamfer cut guide 1751 on either side ofthe saw slots 1218, 1220. Bilateral through holes 1226, 1228 extendthrough the tabs 1222, 1242, respectively, in a distal to proximaldirection. An L-shaped plate 1230 extends anteriorly and proximally fromthe anterior surface 1216. The L-shaped plate 1230 includes an anteriorplate 1231 and a proximal plate 1234. The proximal plate 1234 includes aposterior surface 1236. The proximal surface 1214 is positioned againstthe distal femoral resection 206 and the posterior surface 1236 ispositioned against the top surface 1156 of the femoral pin block 1514 sothat the tabs 1222, 1224 extend medially and laterally relative to thedistal femur 100.

FIG. 114 shows the step of further securing the chamfer cut guide 1751to the distal femur with bone pins 1329. Preferably, this step occurswhile the proximal surface 1214 is in close contact with the distalfemoral resection 206 and the posterior surface 1236 is in close contactwith the top surface 1156.

FIG. 115A shows the step of making an anterior chamfer cut 216 and aposterior chamfer cut 218. The anterior chamfer cut 216 is made throughthe anterior saw slot 1218 in the chamfer cut guide 1751. The posteriorchamfer cut 218 is made through the posterior saw slot 1220 in thechamfer cut guide 1751.

The chamfer cut guide 1751 may be removed so that the distal femoralresection 206 may be adjusted as illustrated in FIG. 111B. The chamfercut guide 1751 may then be repositioned so that the anterior andposterior chamfer cuts 216, 218 can also be adjusted.

FIG. 115B shows an optional step of coupling an implant trial 1238 tothe posterior femoral resection 220 and the chamfer cut guide 1751 sothat the knee may be moved through a range of motion to verify that theproper flexion/extension gaps have been established. Preferably, thisstep occurs while the chamfer cut guide 1751 and the distal femoral cutblock assembly 1638 remain secured to the femur.

FIGS. 116A-119B illustrate a group of steps for making the distalfemoral resection 206 and the anterior and posterior chamfer cuts 216,218 that may be performed as an alternative to the steps illustrated inFIGS. 106-115B.

FIG. 116A shows the step of coupling a distal femoral cut guide 1240 tothe distal anterior femur 100 and the three in one cut guide assembly1321 of FIG. 105 with bone pins 1329. An advantage of this step is thatthe original alignment to the mechanical axis 202 of the leg establishedin FIG. 96A is maintained via the femoral pin 1505, the tibial pin 1507,the tibial extension rod assembly 1511, and the target 1882. Referringto FIGS. 116B and 116C, the distal femoral cut guide 1240 includes adistal surface 1242, a proximal surface 1244, an anterior surface 1246,and a posterior surface 1262. A saw slot 1248 and one or more holes 1250extend through the distal femoral cut guide 1240 in an anterior toposterior direction. Five holes 1250, 1252, 1254, 1256, 1258 are shown.The holes may be counterbored at the anterior surface 1246. A tab 1260extends distally from the distal surface 1242. The posterior surface1262 is positioned against the anterior femoral resection 214, the tab1242 is received in the saw slot 1056 of the anterior femoral cut guide1326, and the distal surface 1242 is positioned against the proximalsurface 1052.

FIG. 117A shows the step of removing the femoral pin 1505, three in onecut guide assembly 1321 and tibial extension rod assembly 1511 andmaking the distal femoral resection 206 through the saw slot 1248 of thedistal femoral cut guide 1240.

FIG. 118A shows the step of coupling a chamfer cut guide 1264 to thedistal femur and the distal femoral cut guide 1240 with bone pins 1329.The chamfer cut guide 1264 includes a distal surface 1266, a proximalsurface 1268, and an anterior surface 1270. The chamfer cut guide 1264has two saw slots 1272, 1274 which intersect at the distal surface 1266and diverge anteriorly and posteriorly as they extend toward theproximal surface 1268. Bilateral tabs 1276, 1278 extend from the chamfercut guide 1264 on either side of the saw slots 1272, 1274. Bilateralthrough holes 1280, 1282 extend through the tabs 1276, 1278,respectively, in a distal to proximal direction. A plate 1284 extendsanteriorly from the anterior surface 1270. A slot 1286 extends throughthe plate 1284 in a distal to proximal direction. The proximal surface1268 is positioned against the distal femoral resection 206, the tab1260 of the distal femoral cut guide 1240 is received in the slot 1286of the chamfer cut guide 1264, and the plate 1284 may be positionedagainst the distal surface 1242.

FIGS. 119A and 119B show the step of making anterior and posteriorchamfer cuts 216, 218. The anterior chamfer cut 216 is made through thesaw slot 1272 of the chamfer cut guide 1264 and the posterior chamfercut 218 is made through the saw slot 1274.

FIG. 120 shows the femur 100, tibia 104, and fibula 122 after making theanterior femoral resection 214, the anterior chamfer cut 216, the distalfemoral resection 206, the posterior chamfer cut 218, the posteriorfemoral resection 220, and the proximal tibial resection 210, and afterremoving all instruments. FIG. 120 represents an endpoint for the stepsshown in FIGS. 106-115B or for the steps shown in FIGS. 116A-119B.

FIGS. 121-146B illustrate yet another instrument system 2500.

FIG. 121 shows the step of securing a foot (not shown) in a portion of afoot holder assembly 2870. This step may be similar to or identical tothe step of FIG. 89. The foot holder assembly 2870 includes a footreceiver 2872, a lower bar 2874, a bridge 2878, a target mounting block2880, a dovetail lock 2881, a target 2882, and a thumbscrew 2884. Thebridge 2878, target mounting block 2880, dovetail lock 2881, target2882, and thumbscrew 2884 are shown in FIG. 126. The foot holderassembly 2870 may be similar to or identical to the foot holder assembly870 or 1870.

FIG. 122 shows the step of securing a femoral support arm assembly 2786to an operating table (not shown) so that a portion of the femoralsupport arm assembly extends over the hip area. This step may be similarto or identical to the step of FIG. 69 and/or FIG. 90. The femoralsupport arm assembly 2786 includes a post 2788, a bar 2790, a firstclamp body 2792, a second clamp body 2794, a spring 2796, a retainingring 2798, a thumbscrew 2800, and a screw 2802. The femoral support armassembly 2786 may be similar to or identical to the femoral support armassembly 786 or 1786.

FIGS. 123A-123B show the step of positioning a femoral head finder 2918to extend over a center 120 of a head of the femur 100. This step may besimilar to or identical to the step of FIG. 70 and/or FIG. 91. FIG. 123Ais a perspective view and FIG. 123B is a top view. The femoral headfinder 2918 may be similar to or identical to the femoral head finder918 or 1918. Imaging, such as radiographs, fluoroscopy, a C-arm, and thelike, may facilitate positioning the femoral head finder 2918 accuratelyover the center 120 of the femoral head.

Alternatively, the center of the femoral head may be located usingultrasound. Ultrasound equipment may already be present in the operatingroom for preoperative identification of the femoral nerve or otherneurovascular structures. The inventors have observed that the arcs ofthe femoral head and acetabulum show up clearly on ultrasound. The arcof the femoral head or acetabulum may be used to determine the locationof the center of the femoral head. A skin mark may be made over thecenter of the femoral head. The skin mark may be made with a pen, anadhesive sticker, a clip or skin staple, a skin-piercing stud, or thelike. A skin-pinching or skin-penetrating mark may be preferable in thepresence of ultrasound gel. The skin mark may be transferred to thefemoral support arm assembly 2786 with a plumb line, which may besupported by the femoral head finder 2918 on the bar 2790. Line 119 inFIG. 123A indicates the plumb line supported by the femoral head finder2918 and positioned over the skin mark over the center 120 of thefemoral head.

FIG. 124 shows the step of securing a collar 2926 to the bar 2790 besidethe femoral head finder 2918. This step may be similar to or identicalto the step of FIG. 70 and/or FIG. 92. The collar 2926 may be similar toor identical to the collar 926 or 1926.

The preceding steps may be performed before the patient is steriledraped. This is advantageous as it occurs before operative time beginsto toll.

FIG. 125 shows the step of removing the femoral head finder 2918 andsecuring a target clamp assembly 2818 to the bar 2790 beside the collar2926. This step may be similar to or identical to the step of FIG. 71and/or FIG. 93. The target clamp assembly 2818 includes a target 2820, aretaining ring 2822, a first clamp body 2824, a second clamp body 2826,a lever 2828, a link 2830, and a pin 2832. The example shows two links2830 and eight pins 2832. The target clamp assembly 2818 may be similarto or identical to the target clamp assembly 818 or 1818. The femoralsupport arm assembly 2786 with attached collar 2926 may be covered by asterile drape after the femoral head finder 2918 is removed and beforethe target clamp assembly 2818 is coupled to the bar 2790, in a mannersimilar to that shown in FIG. 71.

FIG. 126 shows the step of assembling the bridge 2878, target mountingblock 2880, dovetail lock 2881, target 2882, and thumbscrew 2884 to thelower bar 2874 and the foot receiver 2872 to form a complete foot holderassembly 2870. This step may be similar to or identical to the step ofFIG. 94.

FIG. 127 shows the step of making a small provisional proximal tibialresection 209 at the base of the tibial eminence at the level of thenormal lateral tibial plateau, which may optionally be referred to as atibial sizing notch in situations where the resection 209 is limited toa small area such as the center of the lateral articular surface. Theprovisional proximal tibial resection 209 may involve the anteriorportion of the tibial plateau as shown, or it may be less extensive ormore extensive than shown. For example, the provisional proximal tibialresection 209 may involve only the tibial eminence. The provisionalproximal tibial resection 209 marks the level of the unworn lateraltibial plateau and the actual joint line of the femoral-tibial joint.

FIGS. 128A-128B show the step of coupling a femoral pin block assembly2501 to the anterior distal femur. This step may be similar to oridentical to the step of FIG. 72 and/or FIG. 96A. FIG. 128A is aperspective view and FIG. 128B is a top view. The femoral pin blockassembly 2501 includes a base 2502, a handle 2516, a pin guide 2514, ascrew 2513, and a pin sleeve 2515. The example shows two screws 2513.The femoral pin block assembly 2501 is coupled to a femoral extensionrod assembly 2506. The femoral extension rod assembly 2506 includes anouter rod 2604, an inner rod 2606, a spool 2608, a sleeve 2610, a ring2612, a retaining ring 2614, and a pin 2601. The femoral extension rodassembly 2506 may be similar to or identical to the femoral extensionrod 306, 506, 1506 or the tibial extension rod 313, 511, 1511, 2511. Thespool 2608 rests in the target 2820 so that the femoral extension rodassembly 2506 extends over the center 120 of the femoral head.

FIGS. 129A-129B show perspective views of the femoral pin block assembly2501. The pin guide 2514 includes a first hole 2519 and a second hole2521. The femoral pin block assembly 2501 may be similar to the femoralpin guide assembly 1501 of FIG. 97A. The first hole 2519 includes alongitudinal slot 2523. The first hole 2519 receives the pin sleeve2515. The first hole 2519 may be parallel to the bone contacting surface2518 of the base 2502, or a theoretical bone contacting plane defined byspikes 2538 protruding from the bone contacting surface of the base. Thesecond hole 2521 is anteriorly spaced apart from the first hole. Thesecond hole 2521 may be parallel to the bone contacting surface 2518 ofthe base 2502, or a theoretical bone contacting plane defined by spikes2538 protruding from the bone contacting surface of the base, parallelto the first hole 2519, or aligned to correspond to the upcominganterior femoral resection 214, in other words coplanar with theanterior femoral resection 214. The second hole 2521 may be located sothat a guide wire, k-wire, pin, drill, or the like passed through thesecond hole is aligned with the bone contacting surface 2518 of the base2502, or a theoretical bone contacting plane defined by spikes 2538protruding from the bone contacting surface of the base, or the anteriorfemoral resection 214 (which may be at an angle to the bone contactingsurface 2518 or the theoretical bone contacting plane). Preferably, thesecond hole 2521 is located so that the guide wire, etc. exits theanterior femoral cortex at the distal edge 2517 of the base 2502. Thesecond hole 2521 may be used to confirm that the distal anterior femoralresection 214, discussed below, will intersect the distal anteriorfemoral cortex at a satisfactory location. This ensures that the distalanterior femoral resection 214 is not too deep, so that it notches theanterior femur, and not too shallow, so that the final implant sitsabove the bone surface.

In an alternate arrangement, the hole 2519 may be parallel to thefemoral transverse plane, or in other words, perpendicular to theupcoming distal femoral resection 206. The hole 2521 may also beparallel to the femoral transverse plane, or in other words,perpendicular to the distal femoral resection 206. Optionally, thefemoral pin block assembly 2501 may enable the first and second holes tobe adjusted, together or separately, with respect to the bone contactingsurface 2518 and/or with respect to the mechanical axis 202 of thefemur/leg. Preferably, the adjustability occurs between the distal partof pin guide 2514 and the distal part of base 2502.

FIG. 130 shows the step of placing a femoral pin 2505 into the distalfemur through the pin sleeve 2515 and the first hole 2519 of the femoralpin block assembly 2501. This step may be similar to or identical to thestep of FIG. 98. The femoral pin 2505 encodes information about 1) theproper varus/valgus orientation of the distal femoral resection 206, 2)the flexion/extension orientation of the distal anterior femoralresection 214 and the distal posterior femoral resection 220, 3) themiddle of the trochlear groove (Whiteside's line). The femoral pin 2505enables rotational adjustment of the femoral four-in-one cut guideassembly 3010 about the pin 2505, which ensures proper tracking of thepatella. More specifically, the femoral four-in-one cut guide assembly3010 may be adjusted for varus-valgus rotation about the femoral post3122, which rotates within the hole 3004 created by the femoral pin2505. The distal femoral resection 206, distal anterior femoralresection 214, distal posterior femoral resection 220, femoralfour-in-one cut guide assembly 3010, femoral post 3122, and hole 3004are discussed in greater detail below. FIG. 130 also shows the step ofplacing a femoral pin 2507 into the distal femur through the second hole2521. The femoral pin 2507 may be placed into the distal femurtemporarily to verify that the distal anterior femoral resection 214will intersect the distal anterior femoral cortex at a satisfactorylocation, and then removed. The femoral pin 2505 is preferably a 5 mmdiameter drill. The femoral pin 2507 is preferably a 3.2 mm diameterpin. Note that the femoral pin block assembly 2501 is not pinned to theanterior surface of the femur 100.

FIG. 131 shows the step of removing the pin sleeve 2515 from the firsthole 2519 after the femoral pin 2505 has been placed into the distalfemur. This step may be similar to or identical to the step of FIG. 99.FIG. 131 also shows the step of removing the femoral pin 2507 from thesecond hole 2521.

FIG. 132 shows the step of removing the femoral pin block assembly 2501after the femoral pin 2505 has been placed into the distal femur and thepin sleeve 2515 has been removed from the first hole 2519. This step maybe similar to or identical to the step of FIG. 100. The femoral pin 2505slides laterally out of the first hole 2519 through the slot 2523 (FIG.129B). In other words, the femoral pin block assembly 2501 slidesanteriorly off of the femoral pin 2505.

FIGS. 133A-133B show the step of setting the knee angle to 90 degreeswith a knee angle guide 2930. FIG. 133A is a perspective view and FIG.133B is a side view. The knee angle guide 2930 includes a knee angleframe 2932 and a rod 2934. The knee angle frame 2932 includes a hole2936 which receives the femoral pin 2505 and bilateral holes 2938, 2940which receive the rod 2934. The hole 2938 is used with a right knee andthe hole 2940 is used with a left knee as illustrated. The holes 2938,2940 are parallel to each other. Referring to FIG. 133B, the femoral pin2505 has a central longitudinal axis 2942. The rod 2934 has a centrallongitudinal axis 2944. The orientation of axis 2944 is set by hole 2940which receives the rod 2934, or hole 2938 for a right knee. A 90 degreeangle 2946 exists between axis 2944 and axis 2948 of the left arm 2950of the knee angle frame 2932. A small acute angle 2952 may optionallyexist between axis 2942 and 2948. The angle 2952 may be greater than orequal to zero degrees. The illustrated angle 2952 is 3 degrees. In otherwords, the illustrated axis 2942 is parallel to the distal anteriorfemoral cortex, thus parallel to the distal anterior femoral resection214, and is at an angle of 3 degrees to the distal femoral resection206. In other examples, the axis 2942 may be perpendicular to the distalfemoral resection 206 and would thus form a small acute angle with thedistal anterior femoral resection 214. The illustrated knee angle guide2930 holds the rod 2934 (axis 2944) parallel to the distal femoralresection 206 so that when the proximal tibial resection 210 is made,its slope is accurate.

FIG. 134 shows the step of coupling a distal femoral cut guide assembly2960 to the femur 100. The distal femoral cut guide assembly 2960includes a distal plate 2962, a distal femoral cut guide 2964, and aninterlock 2966. The distal plate 2962 slides over the femoral pin 2505.The interlock 2966 couples the distal femoral cut guide 2964 to thedistal plate 2962 so that the distal femoral cut guide 2964 is free toslide in the anterior-posterior direction relative to the distal plate2962. Two pins 2968, 2970 are shown securing the distal femoral cutguide 2964 to the femur 100.

FIGS. 135A-135B show exploded perspective views of the distal femoralcut guide assembly 2960. The distal plate 2962 includes a medial plateportion 2972, a lateral plate portion 2974, and holes 2976, 2978, 2980,2982, 2984. The distal femoral cut guide 2964 includes a slot 2986,holes 2988, 2990, and holes 2992, 2994, 2996. Each of the holes 2992,2994, 2996 may optionally be a cluster of holes as shown. The interlock2966 includes a body 2998 and two posts 3000, 3002. The femoral pin 2505is received in hole 2976. The post 3000 is received in holes 2988 and2978. The post 3002 is received in holes 2990 and 2980. The pin 2968 isreceived in hole 2992 or another hole in its cluster. The pin 2970 isreceived in hole 2994 or another hole in its cluster. Another pin (notshown) may optionally be received in hole 2996 or another hole in itscluster. A saw blade (not shown) is received in the slot 2986 to make adistal femoral resection 206.

FIG. 136 shows the step of removing the interlock 2966, the distal plate2962, the femoral pin 2505, and making a distal femoral resection 206.The distal femoral resection 206 is made through the saw slot 2986 inthe distal femoral cut guide 2964. Removing the femoral pin 2505 leavesa hole 3004 in the distal femur. The hole 3004 is anterior to thefemoral intramedullary canal in dense strong subtrochlear bone.

FIGS. 137A-137D show the step of coupling a femoral four-in-one cutguide assembly 3010 to the femur 100 and a proximal tibial cut guide3012 to the tibia 104. This step may be similar to the step of FIG.102A. FIG. 137A is a perspective view. FIG. 137B is a detail view of aportion of FIG. 137A. FIG. 137C is a front view. FIG. 137D is a sideview. The four-in-one cut guide assembly 3010 is an adjustable assembly.The four-in-one cut guide assembly 3010 includes an anterior cut guide3014, an anterior chamfer guide 3016, a posterior chamfer guide 3018, aposterior cut guide 3020, a gear assembly 3022, and a screw 3024. Fourscrews 3024 are shown, two in the anterior chamfer guide 3016 and two inthe posterior chamfer guide 3018. The four-in-one cut guide assembly3010 and the proximal tibial cut guide 3012 are adjustably coupledtogether by a latch mechanism 3026. The proximal tibial cut guide 3012is coupled to a tibial extension rod assembly 2511. The tibial extensionrod assembly 2511 includes an outer rod 2605, an inner rod 2607, asleeve 2611, a ring 2613, a pin 2601, and a ball 2617. The tibialextension rod assembly 2511 may be similar to or identical to the tibialextension rod 313, 511, 1511 or the femoral extension rod 306, 506,1506, 2506. The ball 2617 rests in the target 2882 so that the tibialextension rod assembly 2511 extends over the center of the distal tibia104. The femoral four-in-one cut guide assembly 3010 and the proximaltibial cut guide 3012 may be adjusted for varus-valgus rotation aboutthe femoral post 3122 in the hole 3004 to position the ball 2617 in thetarget 2882.

FIGS. 138A-138D show the femoral four-in-one cut guide assembly 3010,the proximal tibial cut guide 3012, and the latch mechanism 3026. FIGS.138A-138B are perspective views. FIGS. 138C-138D are explodedperspective views. The proximal tibial cut guide 3012 includes a body3028 with a proximal undercut channel 3030 defined by side walls 3032,3034, a saw slot 3036, holes 3038, 3040, 3042, a distal arm 3044 whichbifurcates into arms 3046, 3048, which are separated by a slot 3050, andterminates in a compliant pin receiver 3052. The slot 3050 may receivethe tibial pin 1507 in the manner shown in FIG. 102A. The pin receiver3052 receives pin 2601 of the tibial extension rod assembly 2511. Theholes 3038, 3040, 3042 may be clusters of holes as shown. The latchmechanism 3026 includes a body 3054, a lever 3056, and pins 3058, 3060.The body 3054 includes a proximal undercut rail 3062, a distal undercutrail 3064, a grip portion 3066, a recess 3068, and holes 3070, 3072. Thelever 3056 includes a tooth 3074, a notch 3076, a button 3078, a hole3080, and a spring arm 3082. The lever 3056 is received in the recess3068 with the tooth 3074 opposite the grip portion 3066 and the button3078 exposed. The pin 3060 is received in the hole 3070 and the notch3076. The pin 3058 is received in the holes 3072, 3080. The distalundercut rail 3064 is received in the proximal undercut channel 3030 sothat the proximal tibial cut guide 3012 may be adjusted relative to thefemoral four-in-one cut guide assembly 3010 in the proximal-distal orsuperior-inferior direction (relative to the femur).

Optionally, for the purpose of making a provisional tibial resection209, the proximal tibial cut guide 3012 can be positioned anterior anddistal to its illustrated position in FIG. 138A, in other words distalto the posterior cut guide 3020, so that the undercut channel 3180 andthe undercut channel 3030 are aligned to form a continuous undercutchannel so that the proximal tibial cut guide 3012 may be adjustedrelative to the femoral four-in-one cut guide assembly 3010 in theproximal-distal or superior-inferior direction (relative to the femur).The latch mechanism 3026 including body 3054 and lever 3056 would ofcourse be reconfigured to complement this arrangement.

Optionally, the femoral four-in-one cut guide assembly 3010 and theproximal tibial cut guide 3012 may be combined together as a five-in-onecut guide assembly. In this arrangement, the proximal tibial cut guide3012 may be adjustable relative to the femoral four-in-one cut guideassembly 3010 in the anterior-posterior direction (relative to thefemur), and may also be adjustable in the proximal-distal direction. Thegear assembly 3022 would of course be reconfigured with additional gearsand a rack to complement this arrangement.

FIGS. 139A-139E show the femoral four-in-one cut guide assembly 3010.FIG. 139A is a front view. FIG. 139B is a cross sectional view takenalong line 139B-139B of FIG. 139A. FIG. 139C is a cross sectional viewtaken along line 139C-139C of FIG. 139A. FIGS. 139D-139E are explodedperspective views. The anterior cut guide 3014 includes a medial sawslot 3124, a lateral saw slot 3126, a plate 3128 with a medial rack3130, a generally rectangular hole 3132, a round hole 3134, a boss 3136,and a femoral post 3122. The generally rectangular hole 3132 includes amedial channel 3250 and a lateral channel 3252. The femoral post 3122 isshown as a separate part coupled to the boss 3136, but the femoral post3122 may be integrally formed with the boss 3136. The illustratedfemoral post 3122 is oriented to match a femoral pin 2505 that isparallel to the bone contacting surface 2518, or theoretical bonecontacting plane, however the femoral post 3122 may be oriented to matcha femoral pin 2505 that is parallel to the femoral transverse plane, orin other words, perpendicular to the distal femoral resection 206.Optionally, the femoral four-in-one cut guide assembly 3010 may bedesigned with a through hole, similar to hole 2976 of distal plate 2962,instead of the femoral post 3122 and boss 3136. The through-hole designmay affect many of the parts in the assembly 3010. The anterior chamferguide 3016 includes a medial saw slot 3138, a lateral saw slot 3140,holes 3142, 3144, holes 3146, 3148, 3150, 3152, and a generallyrectangular channel 3154. The holes 3142, 3144 receive screws 3024. Theholes 3146, 3148, 3150, 3152 may receive bone screws (not shown) and maybe counterbored as shown so that bone screw heads do not occlude the sawslots 3138, 3140. The generally rectangular channel 3154 includes amedial channel 3254, a lateral channel 3256, a medial lip 3262, and alateral lip 3264. The posterior chamfer guide 3018 includes a medial sawslot 3156, a lateral saw slot 3158, holes 3160, 3162, holes 3164, 3166,3168, 3170, and a generally rectangular channel 3172. The holes 3160,3162 receive screws 3024. The holes 3164, 3166, 3168, 3170 may receivebone screws (not shown) and may be counterbored as shown so that bonescrew heads do not occlude the saw slots 3156, 3158. By placing bonescrews through some or all of holes 3146, 3148, 3150, 3152, 3164, 3166,3168, 3170, the anterior chamfer guide 3016 and posterior chamfer guide3018 are locked in place during the sawing process. The bone screws mayserve in lieu of, and may be replaced by, a locking mechanism in thefemoral four-in-one cut guide assembly 3010. The bone screws or lockingmechanism serve to isolate the gear assembly 3022 from loads generatedduring the sawing process. The generally rectangular channel 3172includes a medial channel 3258, a lateral channel 3260, a medial lip3266, and a lateral lip 3268. The plate 3128 slides against the innersurfaces of the lips 3262, 3264, 3266, 3268. The posterior cut guide3020 includes a medial saw slot 3174, a lateral saw slot 3176, agenerally rectangular socket 3178, and a distal undercut channel 3180defined by side walls 3182, 3184. The proximal undercut rail 3062 isreceived in the distal undercut channel 3180 so that the proximal tibialcut guide 3012 may be adjusted relative to the femoral four-in-one cutguide assembly 3010 in the proximal-distal or superior-inferiordirection (relative to the femur). The gear assembly 3022 is received inthe hole 3132, channels 3154, 3172, and socket 3178.

The femoral post 3122 may optionally be included on a bone-facing sideof a conventional four-in-one cut guide, integrally formed or as aseparate part, for engagement with the hole 3004. Alternatively, theconventional four-in-one cut guide may optionally include a through holethat receives the femoral pin 2505. Any of these optional arrangementsenable the conventional four-in-one cut guide to be rotationallyadjusted in the manner described herein for the femoral four-in-one cutguide assembly 3010.

FIGS. 140A-140B are exploded perspective views of the gear assembly3022. The gear assembly 3022 includes a housing 3084, a bolt 3086, abolt head pin 3088, an optional second bolt head pin 3090, a saddleblock 3092, an anterior rack 3094, a posterior rack 3096, a first medialgear 3098, a second medial gear 3100, a third medial gear 3102, a firstlateral gear 3104, a second lateral gear 3106, a third lateral gear3108, a fourth lateral gear 3110, a first shaft 3112, a second shaft3114, a third shaft 3116, a fourth shaft 3118, and a fifth shaft 3120.

The housing 3084 includes holes 3188, 3190, 3192, 3194, 3196, 3198,3200, 3202, 3204, rectangular bosses 3206, 3208, a medial rail 3210, alateral rail 3212, and a window 3214. The hole 3188 receives the bolt3086. The hole 3190 receives the bolt head pin 3088. The optional hole3192 receives the optional second bolt head pin 3090. The boss 3206surrounds the hole 3194. The boss 3208 surrounds the hole 3196. Themedial rail 3210 is received in the medial channels 3250, 3254, 3258.The lateral rail 3212 is received in the lateral channels 3252, 3256,3260. Preferably, the rails 3210, 3212 and channels 3250, 3252, 3254,3256, 3258, 3260 are complementary undercut shapes, such as dovetails(illustrated). The undercut engagement acts to prevent the generallyrectangular channels 3154, 3172 from spreading during heavy use.

The bolt 3086 includes a head 3216, a circumferential groove 3218, ashaft 3220, and a torque drive feature 3222. The groove 3218 receivesthe bolt head pin 3088 and the optional second bolt head pin 3090, ifpresent. The shaft 3220 is at least partially threaded from the endopposite the head 3216.

The saddle block 3092 includes a generally rectangular body 3224, athreaded hole 3226, a boss 3228, and an indentation 3229. The body 3224is received in the window 3214 so that the boss 3228 protrudes from thehousing 3084 near the rails 3210, 3212 and the indentation 3229 facesthe first medial gear 3098. The threaded hole 3226 receives the shaft3220. The boss 3228 is received in the hole 3134.

The anterior rack 3094 includes a rack 3230, a hole 3232, and a hole3234. The holes 3232, 3234 receive screws 3024.

The posterior rack 3096 includes a rack 3236, a hole 3238, and a hole3240. The holes 3238, 3240 receive screws 3024.

Referring to FIGS. 139B-139C, the medial rack 3130 meshes with the firstmedial gear 3098, which is mounted on a hexagonal boss of the secondlateral gear 3106. The second lateral gear 3106 thus rotates with thefirst medial gear 3098. The second lateral gear 3106 meshes with thefirst lateral gear 3104, which meshes with the anterior rack 3094, whichis fastened to the anterior chamfer guide 3016 with screws 3024. Thesecond lateral gear 3106 also meshes with the third lateral gear 3108.The third lateral gear 3108 meshes with the fourth lateral gear 3110,which is mounted on a hexagonal boss of the second medial gear 3100. Thesecond medial gear 3100 thus rotates with the fourth lateral gear 3110.The second medial gear 3100 meshes with the third medial gear 3102,which meshes with the posterior rack 3096, which is fastened to theposterior chamfer guide 3018 with screws 3024.

The first shaft 3112 bears the first medial gear 3098 and the secondlateral gear 3106. The first shaft 3112 is received in hole 3196. Thesecond shaft 3114 bears the second medial gear 3100 and the fourthlateral gear 3110. The second shaft 3114 is received in hole 3198. Thethird shaft 3116 bears the third medial gear 3102. The third shaft 3116is received in hole 3200 and is cantilevered in the window 3214. Thefourth shaft 3118 bears the first lateral gear 3104. The fourth shaft3118 is received in hole 3202 and is cantilevered in the window 3214.The fifth shaft 3120 bears the third lateral gear 3108. The fifth shaft3120 is received in hole 3204 and is cantilevered in the window 3214.

The four-in-one cut guide assembly 3010 can be adjusted to position thesaw slots 3138, 3140, 3156, 3158, 3174, 3176 of the guides 3016, 3018,3020 (respectively) to correspond to the progressive arrangement ofresection surfaces for the range of femoral component sizes of a kneesystem. The saw slots 3124, 3126 of the anterior cut guide 3014 arestationary with respect to the femur 100 because in use the femoral post3122 is in the femoral hole 3004. In the example shown, theanterior-posterior location of each guide 3016, 3018, 3020 isindependently adjustable relative to the anterior cut guide in acontrolled and synchronized manner. The guides are independentlyadjustable because each guide may move relative to the anterior cutguide at its own rate or speed. The adjustments made to each guide arecontrolled and synchronized by the gear assembly 3022 so that turningthe bolt 3088 clockwise and counterclockwise causes each guide to moveat its own speed, and the relative speeds of the guides are selected sothat when the four-in-one cut guide assembly 3010 is adjusted to aparticular size, the saw slots are all positioned to correspond to thatsize. Note the indicia 3186 shown on the housing 3084 in FIG. 140A toindicate prosthesis sizes. An audible, visual, or tactile feedback maybe provided to positively indicate that the femoral four-in-one cutguide assembly 3010 is set to a discrete implant size. Optionally, in anarrangement that lacks such positive indicators, a spacer may be used toverify that the femoral four-in-one cut guide assembly 3010 is set to adiscrete implant size. As one example, a spacer may have one or moreprongs, plates, or fingers that engage one or more of the gaps 3015,3017, 3019 (FIGS. 141C-141D) that occur between the anterior cut guide3014, the anterior chamfer guide 3016, the posterior chamfer guide 3018,and the posterior cut guide 3020 of the femoral four-in-one cut guideassembly 3010. The spacer may be removed before making any resections.The relative speeds of the guides are a matter of design choice and willchange from one knee system to the next. The example shown providesproportional motion of the guides 3016, 3018, 3020 relative to theanterior cut guide 3014. It is also contemplated that non-proportionalmotion may be provided, so that one or more of the guides may movesometimes faster and sometimes slower, according to the design rationaleof the particular knee system.

FIGS. 141A-141D show the step of adjusting the femoral four-in-one cutguide assembly 3010, adjusting the proximal tibial cut guide 3012, andpinning the femoral four-in-one cut guide assembly 3010 and the proximaltibial cut guide 3012 to the femur 100 and the tibia 104, respectively.The femoral four-in-one cut guide assembly 3010 and the proximal tibialcut guide 3012 may be adjusted for varus-valgus rotation about thefemoral post 3122 in the hole 3004. The femoral four-in-one cut guideassembly 3010 may be adjusted for size by rotating the bolt 3088clockwise and counterclockwise to change the anterior-posteriorlocations of the saw slots 3138, 3140, 3156, 3158, 3174, 3176 of theguides 3016, 3018, 3020 (respectively). The proximal tibial cut guide3012 is coupled to the femoral four-in-one cut guide assembly 3010 bythe latch mechanism 3026, which fixes the saw slot 3036 a predeterminedanterior-posterior distance from the saw slots 3174, 3176 and allows theproximal tibial cut guide 3012 to slide in and out over the tibialplateau. Preferably, the femoral four-in-one cut guide assembly 3010 isadjusted by first rotating the bolt 3088 until the femoral four-in-onecut guide assembly 3010 is in its closed or smallest state (shown inFIGS. 137A-139C) and then rotating the bolt 3088 in the oppositedirection to move the femoral four-in-one cut guide assembly 3010 towardits fully open or largest state, until the proximal tibial cut guide3012 contacts the provisional tibial resection 209 (shown in FIGS.141B-142). At this point, if the femoral four-in-one cut guide assembly3010 is between sizes, the bolt 3088 may be rotated to adjust thefemoral four-in-one cut guide assembly 3010 to the next smaller size.Pins 3242, 3244, 3246, 3248 secure the femoral four-in-one cut guideassembly 3010 and the proximal tibial cut guide 3012 to the femur 100and tibia 104, respectively. Pin 3242 is received in hole 3194, pin 3244is received in hole 3038, pin 3246 is received in hole 3040, and pin3248 is received in slot 3050.

FIG. 142 shows the step of making an anterior femoral resection 214, ananterior chamfer cut 216, a posterior chamfer cut 218, a posteriorfemoral resection 220, and a proximal tibial resection 210. The anteriorfemoral resection 214 is made through the saw slots 3124, 3126 in theanterior cut guide 3014. The anterior chamfer cut 216 is made throughthe saw slots 3138, 3140 in the anterior chamfer guide 3016. Theposterior chamfer cut 218 is made through the saw slots 3156, 3158 inthe posterior chamfer guide 3018. The posterior femoral resection 220 ismade through the saw slots 3174, 3176 in the posterior cut guide 3020.The proximal tibial resection 210 is made through the saw slot 3036 inthe proximal tibial cut guide 3012.

FIG. 143 shows the step of removing the femoral four-in-one cut guideassembly 3010, the proximal tibial cut guide 3012, the tibial extensionrod assembly 2511, and related pins after making the anterior femoralresection 214, the anterior chamfer cut 216, the posterior chamfer cut218, the posterior femoral resection 220, and the proximal tibialresection 210. This step may be similar to or identical to the step ofFIG. 120.

FIG. 144 shows the step of implanting a femoral component 130, a tibialcomponent 132, an articular insert 134, and a patellar component 136 inthe prepared knee joint. This step may be similar to or identical to thestep of FIG. 88. The femoral component 130 is fixed to the distal femur100, the tibial component 132 is fixed to the proximal tibia 104, thearticular insert 134 is coupled to the tibial component 132, and thepatellar component 136 is fixed to the patella 112. The implantcomponents shown in FIG. 144 are one example of a set of implantcomponents for knee arthroplasty. A subset of the components shown mayalso be used. Unicompartmental components may also be used.

FIG. 145 shows the step of converting from an intramedullary referencingsystem or other conventional referencing system to the system disclosedherein by coupling another femoral pin block assembly 3270 of thepresent system to a distal femoral cut guide 3272 of the conventionalreferencing system and placing a femoral pin 2505 into the distal femurthrough the pin sleeve 2515. This step may take place instead of thesteps of coupling the femoral pin block assembly 2501 to the anteriordistal femur, as shown in FIG. 128A, and placing the femoral pin 2505into the distal femur through the pin sleeve 2515 and the first hole2519 of the femoral pin block assembly 2501, as shown in FIG. 130. Thestep of FIG. 145 may result in equivalent positioning of the femoral pin2505 in the distal femur, as shown in FIG. 132, including formation ofan equivalent hole 3004. The step of FIG. 145 may occur after a distalfemoral resection 206 and a provisional proximal tibial resection 209have been made.

FIGS. 146A-146B are exploded perspective views of the femoral pin blockassembly 3270 and the distal femoral cut guide 3272. The femoral pinblock assembly 3270 includes a body 3274, the pin sleeve 2515, ananterior referencing pin 3276, and a thumbscrew 3278.

The body 3274 includes a pin guide arm 3280, a distal femoral paddle3282, and an anterior referencing arm 3284. The pin guide arm 3280includes a first hole 3286 with a longitudinal slot 3288, equivalent tothe first hole 2519 and longitudinal slot 2523. The first hole 3286receives the pin sleeve 2515, which receives the femoral pin 2505. Theslot 3288 is wider than the femoral pin 2505. The pin guide arm 3280 mayinclude an optional second hole (not shown) equivalent to the secondhole 2521. The anterior referencing arm 3284 includes a first hole 3290,a slot 3292, and a second hole 3294. The first hole 3290 receives theanterior referencing pin 3276. The slot 3292 splits the first hole 3290longitudinally and bifurcates the free end of the arm 3284. The secondhole 3294 extends through the bifurcated free ends of the arm 3284transverse to the first hole 3290. The second hole 3294 threadedlyreceives the thumbscrew 3278, which can be tightened so that the firsthole 3290 grips the anterior referencing pin 3276, or loosened so thatthe anterior referencing pin is movable within the first hole.

The anterior referencing pin 3276 extends between a narrow distal end3296 and a broad proximal end 3298. The distal end 3296 contacts theanterior distal femoral cortex in use, while the proximal end 3298serves as a handle. The distal end 3296 may taper to a point as shown.The proximal end 3298 may include grip features 3300 such as grooves(shown), knurling, threads, bumps, or a rough surface texture. Theanterior referencing pin 3276 may optionally include indicia 3302, bestseen in the enlarged detail provided in FIG. 146B. The indicia 3302 mayinclude reference lines, numerals, icons, or other marks.

The distal femoral cut guide 3272 includes a saw slot 3304, pin holes3306, 3308, 3310, and holes 3312, 3314. The saw slot 3304 receives a sawblade (not shown) to make the distal femoral resection 206. The saw slot3304 also receives the distal femoral paddle 3282 as shown in FIG. 145.The pin holes 3306, 3308, 3310 receive bone pins 3316. Each pin hole3306, 3308, 3310 may be a cluster of holes as shown. Indicia 3318 may bepresent.

Any methods disclosed herein comprise one or more steps or actions forperforming the described method. The method steps and/or actions may beinterchanged with one another. In other words, unless a specific orderof steps or actions is required for proper operation of the embodiment,the order and/or use of specific steps and/or actions may be modified.

Reference throughout this specification to “an embodiment” or “theembodiment” means that a particular feature, structure or characteristicdescribed in connection with that embodiment is included in at least oneembodiment. Thus, the quoted phrases, or variations thereof, as recitedthroughout this specification are not necessarily all referring to thesame embodiment.

Similarly, it should be appreciated that in the above description ofembodiments, various features are sometimes grouped together in a singleembodiment, figure, or description thereof for the purpose ofstreamlining the disclosure. This method of disclosure, however, is notto be interpreted as reflecting an intention that any claim in this orany application claiming priority to this application require morefeatures than those expressly recited in that claim. Rather, as thefollowing claims reflect, inventive aspects lie in a combination offewer than all features of any single foregoing disclosed embodiment.Thus, the claims following this Detailed Description are herebyexpressly incorporated into this Detailed Description, with each claimstanding on its own as a separate embodiment. This disclosure includesall permutations of the independent claims with their dependent claims.

Recitation in the claims of the term “first” with respect to a featureor element does not necessarily imply the existence of a second oradditional such feature or element. Elements recited inmeans-plus-function format are intended to be construed in accordancewith 35 U.S.C. § 112 Para. 6. It will be apparent to those having skillin the art that changes may be made to the details of theabove-described embodiments without departing from the underlyingprinciples of the technology.

While specific embodiments and applications of the present technologyhave been illustrated and described, it is to be understood that thetechnology is not limited to the precise configuration and componentsdisclosed herein. Various modifications, changes, and variations whichwill be apparent to those skilled in the art may be made in thearrangement, operation, and details of the methods and systems of thetechnology disclosed herein without departing from the spirit and scopeof the invention as claimed.

The invention claimed is:
 1. A method for knee arthroplasty, comprisingthe steps of: making a provisional proximal tibial resection at a baseof a tibial eminence of a tibia of a knee joint; positioning the kneejoint in 90 degrees of flexion, wherein the knee joint comprises a femurand the tibia; making a hole in a distal aspect of the femur, parallelto a mechanical axis of the femur and displaced from an intramedullarycanal of the femur; coupling a cut guide assembly to the femur and thetibia by inserting a pin or a post of the cut guide assembly into thehole parallel to the mechanical axis of the femur, wherein the cut guideassembly comprises a posterior femoral saw slot, a proximal tibial sawslot, and a tibia-contacting feature; and contacting the provisionalproximal tibial resection with the tibia-contacting feature to positionthe posterior femoral saw slot a predetermined first distance superiorto the provisional proximal tibial resection and to position theproximal tibial saw slot a predetermined second distance inferior to theprovisional proximal tibial resection.
 2. The method of claim 1, whereinthe provisional proximal tibial resection involves only the tibialeminence.
 3. The method of claim 1, wherein making the hole in thedistal aspect of the femur comprises making the hole in subtrochlearbone anterior to an intramedullary canal of the femur.
 4. The method ofclaim 3, wherein in a lateral view, the hole is parallel with anexterior distal anterior cortical region of the femur, wherein in ananterior view, the cortical region is centered on the mechanical axis ofthe femur and located adjacent to and proximal to a proximal edge of anatural articular surface of the femur.
 5. The method of claim 3,wherein the cut guide assembly comprises a tibial extension rodterminating in a distal tip, the method comprising the steps of:rotating the cut guide assembly about the post in the hole to center thedistal tip of the tibial extension rod in a medial-lateral width of adistal portion of the tibia; making a posterior femoral resectionthrough the posterior femoral saw slot; and making a final proximaltibial resection through the proximal tibial saw slot.
 6. The method ofclaim 3, wherein the cut guide assembly comprises an anterior femoralsaw slot that is located a fixed third distance away from the post;wherein contacting the provisional proximal tibial resection with thetibia-contacting feature positions the posterior femoral saw slot afourth distance inferior to the anterior femoral saw slot, wherein thecut guide assembly comprises indicia which indicate an implant size thatcorresponds to the fourth distance.
 7. The method of claim 1, whereincoupling the cut guide assembly to the femur comprises inserting the pininto a hole of the cut guide assembly.
 8. The method of claim 7, whereinin a lateral view, the pin is parallel with an exterior distal anteriorcortical region of the femur, wherein in an anterior view, the corticalregion is centered on the mechanical axis of the femur and locatedadjacent to and proximal to a proximal edge of a natural articularsurface of the femur.
 9. The method of claim 7, wherein the cut guideassembly comprises a tibial extension rod terminating in a distal tip,the method comprising the steps of: rotating the cut guide assemblyabout the pin in the hole to center the distal tip of the tibialextension rod in a medial-lateral width of a distal portion of thetibia; making a posterior femoral resection through the posteriorfemoral saw slot; and making a final proximal tibial resection throughthe proximal tibial saw slot.
 10. The method of claim 7, wherein the cutguide assembly comprises an anterior femoral saw slot that is located afixed third distance away from the post; wherein contacting theprovisional proximal tibial resection with the tibia-contacting featurepositions the posterior femoral saw slot a fourth distance inferior tothe anterior femoral saw slot, wherein the cut guide assembly comprisesindicia which indicate an implant size that corresponds to the fourthdistance.
 11. A method for knee arthroplasty, comprising the steps of:making a provisional proximal tibial resection at a base of a tibialeminence of a tibia of a knee joint, wherein the knee joint comprisesthe tibia and a femur; coupling a cut guide assembly to a distal end ofthe tibia; positioning the knee joint in 90 degrees of flexion; couplingthe cut guide assembly to the femur, wherein the cut guide assemblycomprises a first femoral saw slot, a proximal tibial saw slot, and atibia-contacting feature; wherein the first femoral saw slot comprises aposterior femoral saw slot; contacting the provisional proximal tibialresection with the tibia-contacting feature to fix the first femoral sawslot a predetermined first distance superior to the provisional proximaltibial resection and to fix the proximal tibial saw slot a predeterminedsecond distance inferior to the provisional proximal tibial resection.12. The method of claim 11, wherein the provisional proximal tibialresection involves only the tibial eminence.
 13. The method of claim 11,comprising the step of: making a hole in a distal aspect of the femur insubtrochlear bone anterior to an intramedullary canal of the femur;wherein coupling the cut guide assembly to the femur comprises insertinga post of the cut guide assembly into the hole.
 14. The method of claim13, wherein in an anterior view, the hole is parallel to a mechanicalaxis of the femur, wherein in a lateral view, the hole is parallel withan exterior distal anterior cortical region of the femur, wherein in ananterior view, the cortical region is centered on the mechanical axis ofthe femur and located adjacent to and proximal to a proximal edge of anatural articular surface of the femur.
 15. The method of claim 13,wherein the cut guide assembly comprises a tibial extension rodterminating in a distal tip, the method comprising the steps of:centering the distal tip of the tibial extension rod in a medial-lateralwidth of a distal portion of the tibia; making a first femoral resectionthrough the first femoral saw slot; and making a final proximal tibialresection through the proximal tibial saw slot.
 16. The method of claim13, wherein the cut guide assembly comprises a second femoral saw slotthat is located a fixed third distance away from the post; whereincontacting the provisional proximal tibial resection with thetibia-contacting feature positions the first femoral saw slot a fourthdistance inferior to the second femoral saw slot, wherein the cut guideassembly comprises indicia which indicate an implant size thatcorresponds to the fourth distance.
 17. The method of claim 11,comprising the step of: inserting a pin into a distal aspect of thefemur in subtrochlear bone anterior to an intramedullary canal of thefemur; wherein coupling the cut guide assembly to the femur comprisesinserting the pin into a hole of the cut guide assembly.
 18. The methodof claim 17, wherein in an anterior view, the pin is parallel to amechanical axis of the femur, wherein in a lateral view, the pin isparallel with an exterior distal anterior cortical region of the femur,wherein in an anterior view, the cortical region is centered on themechanical axis of the femur and located adjacent to and proximal to aproximal edge of a natural articular surface of the femur.
 19. Themethod of claim 17, wherein the cut guide assembly comprises a tibialextension rod terminating in a distal tip, the method comprising thesteps of: rotating the cut guide assembly about the pin in the hole tocenter the distal tip of the tibial extension rod in a medial-lateralwidth of a distal portion of the tibia; making a first femoral resectionthrough the first femoral saw slot; and making a final proximal tibialresection through the proximal tibial saw slot.
 20. The method of claim17, wherein the cut guide assembly comprises a second femoral saw slotthat is located a fixed third distance away from the post; whereincontacting the provisional proximal tibial resection with thetibia-contacting feature positions the first femoral saw slot a fourthdistance inferior to the second femoral saw slot, wherein the cut guideassembly comprises indicia which indicate an implant size thatcorresponds to the fourth distance.
 21. A method for arthroplasty of aknee joint comprising a femur and a tibia, the method comprising: makinga provisional proximal tibial resection at an anterior aspect of a baseof a tibial eminence of a proximal end of the tibia; positioning theknee joint in 90 degrees of flexion; coupling a cut guide assembly tothe femur and the tibia, wherein the cut guide assembly comprises aposterior femoral saw slot, a proximal tibial saw slot, and atibia-contacting feature located between the posterior femoral saw slotand the proximal tibial saw slot, wherein the proximal tibial saw slotis a fixed first distance from the posterior femoral saw slot along ananterior-posterior direction relative to the femur, wherein thetibia-contacting feature is a fixed second distance from the posteriorfemoral saw slot along the anterior-posterior direction, wherein thefirst distance is greater than the second distance; and contacting onlythe anterior aspect of the provisional proximal tibial resection withthe tibia-contacting feature.
 22. The method of claim 21, comprising thestep of: making a hole in a distal aspect of the femur in subtrochlearbone anterior to an intramedullary canal of the femur; wherein couplingthe cut guide assembly to the femur comprises inserting a post of thecut guide assembly into the hole.
 23. The method of claim 22, wherein inan anterior view, the hole is parallel to a mechanical axis of thefemur, wherein in a lateral view, the hole is parallel with an exteriordistal anterior cortical region of the femur, wherein in an anteriorview, the cortical region is centered on the mechanical axis of thefemur and located adjacent to and proximal to a proximal edge of anatural articular surface of the femur.
 24. The method of claim 22,wherein the cut guide assembly comprises a tibial extension rodterminating in a distal tip, the method comprising the steps of:rotating the cut guide assembly about the post in the hole to center thedistal tip of the tibial extension rod in a medial-lateral width of adistal portion of the tibia; making a posterior femoral resectionthrough the posterior femoral saw slot; and making a final proximaltibial resection through the proximal tibial saw slot.
 25. The method ofclaim 22, wherein the cut guide assembly comprises an anterior femoralsaw slot that is located a fixed third distance away from the post;wherein contacting the provisional proximal tibial resection with thetibia-contacting feature positions the posterior femoral saw slot afourth distance inferior to the anterior femoral saw slot, wherein thecut guide assembly comprises indicia which indicate an implant size thatcorresponds to the fourth distance.
 26. The method of claim 21,comprising the step of: inserting a pin into a distal aspect of thefemur in subtrochlear bone anterior to an intramedullary canal of thefemur; wherein coupling the cut guide assembly to the femur comprisesinserting the pin into a hole of the cut guide assembly.
 27. The methodof claim 26, wherein in an anterior view, the pin is parallel to amechanical axis of the femur, wherein in a lateral view, the pin isparallel with an exterior distal anterior cortical region of the femur,wherein in an anterior view, the cortical region is centered on themechanical axis of the femur and located adjacent to and proximal to aproximal edge of a natural articular surface of the femur.
 28. Themethod of claim 26, wherein the cut guide assembly comprises a tibialextension rod terminating in a distal tip, the method comprising thesteps of: rotating the cut guide assembly about the pin in the hole tocenter the distal tip of the tibial extension rod in a medial-lateralwidth of a distal portion of the tibia; making a posterior femoralresection through the posterior femoral saw slot; and making a finalproximal tibial resection through the proximal tibial saw slot.
 29. Themethod of claim 26, wherein the cut guide assembly comprises an anteriorfemoral saw slot that is located a fixed third distance away from thepost; wherein contacting the provisional proximal tibial resection withthe tibia-contacting feature positions the posterior femoral saw slot afourth distance inferior to the anterior femoral saw slot, wherein thecut guide assembly comprises indicia which indicate an implant size thatcorresponds to the fourth distance.